Nguyễn Phúc Tâm

//DQBN23
uses math;
var
  n, i, s: longint;
  res: int64;
  a, b: array[-7..1000007] of longint;
  f: array[-7..100007] of boolean;
procedure erathos(u: longint);
var i, j: longint;
begin
    for i := 1 to u do f[i] := true;
    f[1] := false;
    i := 2;
    while i*i <= u do
      if f[i] then
        begin
            j := 2;
            while i*j <= u do
              begin
                  f[i*j] := false;
                  inc(j);
              end;
            inc(i);
        end
      else inc(i);
end;
procedure solve();
var p: longint;
    tam: int64;
begin
    tam := 0;
    for p := 1 to n do
      if b[p] = 1 then inc(tam,a[p]);
    if f[tam] then res := max(res, tam);
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          b[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'dqbn23.inp');reset(input);
    assign(output,'dqbn23.out');rewrite(output);
    readln(n);
    s := 0;
    for i := 1 to n do
      begin
          read(a[i]);
          inc(s, a[i]);
      end;
    res := low(longint);
    erathos(s);
    try(1);
    writeln(res);
    close(input);close(output);
end.

//DQBN22
uses math;
var
  n, i: longint;
  a, b: array[-7..1000007] of longint;
function prime(u: int64): boolean;
var j: longint;
begin
    if u <= 1 then exit(false);
    for j := 2 to trunc(sqrt(u)) do
      if u mod j = 0 then exit(false);
    exit(true);
end;
procedure solve();
var p: longint;
    tam: int64;
begin
    tam := 0;
    for p := 1 to n do
      if b[p] = 1 then inc(tam,a[p]);
    if prime(tam) = false then exit();
    for p := 1 to n do
      if b[p] = 1 then write(a[p],#32);
    writeln();
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          b[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'dqbn22.inp');reset(input);
    assign(output,'dqbn22.out');rewrite(output);
    readln(n);
    for i := 1 to n do read(a[i]);
    try(1);
    close(input);close(output);
end.

//EMERALD
var
  n, i, s, q: longint;
  a, b: array[-7..100007] of longint;
procedure solve();
var p: longint;
    tam: int64;
begin
    tam := 0;
    for p := 1 to n do
    if b[p] = 1 then
      begin
          inc(tam, a[p]);
          if tam > s div 3 then exit();
      end;
    if tam <> s div 3 then exit();
    writeln(tam);
    q := 1;
    for p := 1 to n do
      if b[p] = 1 then write(p,#32);
    writeln();
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          if q = 1 then exit();
          b[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'emerald.inp');reset(input);
    assign(output,'emerald.out');rewrite(output);
    readln(n);
    s := 0;
    for i := 1 to n do
      begin
          read(a[i]);
          inc(s, a[i]);
      end;
    if s mod 3 <> 0 then writeln(0)
    else
      begin
          q := 0;
          try(1);
      end;
    close(input);close(output);
end.

//MODM
var
  n, m, i, g, res, k: longint;
  a, b, d: array[-7..100007] of longint;
procedure solve();
var p, q, h: longint;
    c: array[-7..100007] of longint;
begin
    k := 0;
    for p := 1 to n do
      if b[p] = 1 then
        begin
            inc(k);
            c[k] := a[p];
        end;
    for p := 1 to k-1 do
      for q := p+1 to k do
        if (c[p] + c[q]) mod m = 0 then exit();
    if k > res then
      begin
          res := k;
          h := 0;
          for p := 1 to n do
            if b[p] = 1 then
              begin
                  inc(h);
                  d[h] := p;
              end;
      end;
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          b[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'modm.inp');reset(input);
    assign(output,'modm.out');rewrite(output);
    readln(n, m);
    for i := 1 to n do read(a[i]);
    try(1);
    writeln(res);
    for i := 1 to res do write(d[i],#32);
    close(input);close(output);
end.

//FINANCIAL
var
  n, k, i, res: longint;
  a, b, g: array[-7..100007] of longint;
procedure solve();
var p, d, h: longint;
    c: array[-7..100007] of longint;
begin
    h := 0;d := 0;
    for p := 1 to n do
      if b[p] = 1 then
        begin
            inc(d);
            inc(h);
            c[h] := a[p];
        end;
    for p := 1 to h-1 do
      if abs(c[p+1] - c[p]) < k then exit();
    if d > res then
      begin
          res := d;
          for p := 1 to res do g[p] := c[p];
      end;
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          b[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'financial.inp');reset(input);
    assign(output,'financial.out');rewrite(output);
    readln(n, k);
    for i := 1 to n do read(a[i]);
    res := low(longint);
    try(1);
    writeln(res);
    for i := 1 to res do write(g[i],#32);
    close(input);close(output);
end.

//BINARY
var
  n, res: longint;
  s: string;
  a: array[-7..100007] of longint;
procedure solve();
var p, d: longint;
    sa: string;
begin
    sa := '';
    d := 0;
    for p := 1 to n do
      if a[p] = 1 then sa := sa + '1'
      else sa := sa + '0';
    while pos(s, sa) > 0 do
      begin
          inc(d);
          if d > 1 then exit();
          sa := copy(sa, pos(s, sa) + length(s), length(sa) - pos(s, sa) + length(s));
      end;
    if d = 1 then inc(res);
end;
procedure try(i: longint);
var j: longint;
begin
    for j := 0 to 1 do
      begin
          a[i] := j;
          if i = n then solve()
          else try(i+1);
      end;
end;
begin
    assign(input,'binary.inp');reset(input);
    assign(output,'binary.out');rewrite(output);
    readln(n);
    readln(s);
    res := 0;
    try(1);
    writeln(res);
    close(input);close(output);
end.

//DQCKN1
var
  n, k, ii: longint;
  a: array[-7..100007] of longint;
  f: array[-7..100007] of boolean;
procedure solve();
var p: longint;
begin
    for p := 1 to k do write(a[p],#32);
    writeln();
end;
procedure tryh(i: longint);
var j: longint;
begin
    for j := a[i-1]+1 to n-k+i do
      begin
          a[i] := j;
          if i = k then solve()
          else tryh(i+1);
      end;
end;
begin
    assign(input,'dqckn1.inp');reset(input);
    assign(output,'dqckn1.out');rewrite(output);
    readln(n, k);
    for ii := 1 to n do f[ii] := true;
    tryh(1);
    close(input);close(output);
end.

//DQCKN2
var
  n, k, s, i: longint;
  a, b: array[-7..100007] of longint;
procedure solve();
var p: longint;
    sb: int64;
begin
    sb := 0;
    for p := 1 to k do
      begin
          sb := sb + b[a[p]];
          if sb > s then exit();
      end;
    if sb = s then
      begin
          for p := 1 to k do write(b[a[p]],#32);
          writeln();
      end;
end;
procedure tryh(i: longint);
var j: longint;
begin
    for j := a[i-1]+1 to n-k+i do
      begin
          a[i] := j;
          if i = n then solve()
          else tryh(i+1);
      end;
end;
begin
    assign(input,'dqckn2.inp');reset(input);
    assign(output,'dqckn2.out');rewrite(output);
    readln(n, k, s);
    for i := 1 to n do read(b[i]);
    tryh(1);
    close(input);close(output);
end.

//DQCKN4
uses math;
var
  n, k, ii, res: longint;
  a, b: array[-7..100007] of longint;
function pali(u: longint): boolean;
var tam, v: longint;
begin
    tam := 0;v := u;
    while u > 0 do
      begin
          tam := tam * 10 + (u mod 10);
          u := u div 10;
      end;
    exit(v = tam);
end;
procedure solve();
var p: longint;
    sa: int64;
begin
    sa := 0;
    for p := 1 to k do sa := sa + a[b[p]];
    if (pali(sa)) then res := max(res, sa);
end;
procedure tryh(i: longint);
var j: longint;
begin
    for j := b[i-1]+1 to n-k+i do
      begin
          b[i] := j;
          if i = k then solve()
          else tryh(i+1);
      end;
end;
begin
    assign(input,'dqckn4.inp');reset(input);
    assign(output,'dqckn4.out');rewrite(output);
    readln(n, k);
    for ii := 1 to n do read(a[ii]);
    res := low(longint);
    tryh(1);
    writeln(res);
    close(input);close(output);
end.

//DQCKN51
uses math;
var
  n, k, ii, rmin, rmax: longint;
  a, b: array[-7..100007] of longint;
procedure solve();
var p, d1, d2: longint;
begin
    d1 := 0;d2 := 0;
    for p := 1 to k do
      if b[a[p]] = rmin then d1 := 1
      else if b[a[p]] = rmax then d2 := 1;
    if (d1 = 1) and (d1 = d2) then
      begin
          for p := 1 to k do write(b[a[p]],#32);
          writeln();
      end;
end;
procedure tryh(i: longint);
var j: longint;
begin
    for j := a[i-1]+1 to n-k+i do
      begin
          a[i] := j;
          if i = k then solve()
          else tryh(i+1);
      end;
end;
begin
    assign(input,'dqckn51.inp');reset(input);
    assign(output,'dqckn51.out');rewrite(output);
    readln(n, k);
    rmax := low(longint);
    rmin := high(longint);
    for ii := 1 to n do
      begin
          read(b[ii]);
          rmin := min(rmin, b[ii]);
          rmax := max(rmax, b[ii]);
      end;
    tryh(1);
    close(input);close(output);
end.

//xau2
var
  s: string;
function kt(u: string): boolean;
var z: string;
    j: longint;
begin
    z := '';
    for j := length(u) downto 1 do z := z + u[j];
    if z = u then exit(true)
    else exit(false);
end;
begin
    assign(input,'xau2.inp');reset(input);
    assign(output,'xau2.out');rewrite(output);
    readln(s);
    writeln(kt(s));
    close(input);close(output);
end.

//xau3
var
  s: string;
procedure ch();
begin
    while pos('  ', s) > 0 do delete(s, pos('  ', s), 1);
    if s[1] = ' ' then delete(s, 1, 1);
    if s[length(s)] = ' ' then delete(s, length(s), 1);
end;
begin
    assign(input,'xau3.inp');reset(input);
    assign(output,'xau3.out');rewrite(output);
    readln(s);
    ch;
    writeln(s);
    close(input);close(output);
end.

//xau4
var
  s: string;
  i: longint;
  j: char;
  d: array['a'..'z'] of longint;
begin
    assign(input,'xau4.inp');reset(input);
    assign(output,'xau4.out');rewrite(output);
    readln(s);
    for i := 1 to length(s) do inc(d[s[i]]);
    for j := 'a' to 'z' do
      if d[j] <> 0 then writeln(j,#32,d[j]);
    close(input);close(output);
end.

//xau5
var
  s, tam: string;
  i, k, t: longint;
  c: array[-7..100007] of longint;
begin
    assign(input,'xau5.inp');reset(input);
    assign(output,'xau5.out');rewrite(output);
    readln(s);
    k := 0;
    while i < length(s) do
      begin
          inc(i);
          tam := '';
          while s[i] in ['0'..'9'] do
            begin
                tam := tam + s[i];
                inc(i);
            end;
          if tam <> '' then
            begin
                inc(k);
                val(tam, t);
                c[k] := t;
            end;
      end;
    for i := 1 to k do writeln(c[i],#32);
    close(input);close(output);
end.

//xau6
uses math;
var
  s, tam: string;
  i, k, t, res: longint;
  c: array[-7..100007] of longint;
begin
    assign(input,'xau6.inp');reset(input);
    assign(output,'xau6.out');rewrite(output);
    readln(s);
    k := 0;
    res := low(longint);
    while i < length(s) do
      begin
          inc(i);
          tam := '';
          while s[i] in ['0'..'9'] do
            begin
                tam := tam + s[i];
                inc(i);
            end;
          if tam <> '' then
            begin
                inc(k);
                val(tam, t);
                c[k] := t;
            end;
      end;
    for i := 1 to k do res := max(res, c[i]);
    writeln(res);
    close(input);close(output);
end.

//xau7
var
  s, snen, tam, r: string;
  i, d: longint;
begin
    assign(input,'xau7.inp');reset(input);
    assign(output,'xau7.out');rewrite(output);
    readln(s);
    i := 0;
    while i < length(s) do
      begin
          inc(i);
          tam := s[i];
          d := 1;
          while s[i] = s[i+1] do
            begin
                inc(d);
                inc(i);
            end;
          str(d, r);
          snen := snen + tam + r;
      end;
    writeln(snen);
    close(input);close(output);
end.

//xau8
var
  s, tam, sg: string;
  i, k, t, n, j: longint;
  c: array[-7..100007] of longint;
begin
    assign(input,'xau8.inp');reset(input);
    assign(output,'xau8.out');rewrite(output);
    readln(s);
    k := 0;
    sg := '';
    while i < length(s) do
      begin
          inc(i);
          tam := '';
          while s[i] in ['0'..'9'] do
            begin
                tam := tam + s[i];
                inc(i);
            end;
          if tam <> '' then
            begin
                val(tam, n);
                for j := 1 to n do sg := sg + s[i-length(tam)-1];
            end;
      end;
    writeln(sg);
    close(input);close(output);
end.

//xau9
var
  s, s1: string;
function xx(u, v: string): string;
begin
    while pos(u, v) > 0 do delete(v, pos(u, v), length(u));
    exit(v);
end;
begin
    assign(input,'xau9.inp');reset(input);
    assign(output,'xau9.out');rewrite(output);
    readln(s);
    readln(s1);
    writeln(xx(s1, s));
    close(input);close(output);
end.

//b10(xau)
uses math;
var
  s, s0: string;
  i, j, res: longint;
function kt(u: string): boolean;
var p: longint;
    v: string;
begin
    v := '';
    for p := length(u) downto 1 do v := v + u[p];
    exit(u = v);
end;
begin
    assign(input,'xau10.inp');reset(input);
    assign(output,'xau10.out');rewrite(output);
    readln(s);
    res := low(longint);
    for i := 1 to length(s) do
      for j := i to length(s) do
        begin
            s0 := copy(s, i, j-i+1);
            if kt(s0) then res := max(res, j-i+1);
        end;
    writeln(res);
    close(input);close(output);
end.

//bai11(xau ki tu)
var
  n, i: longint;
  s0: string;
  a: array[-7..1000007] of longint;
  s: array[-7..1000007] of string;
procedure bbs();
var p, q: longint;
    tam: string;
begin
    for p := 1 to n-1 do
      for q := p+1 to n do
        if s[p] < s[q] then
          begin
              tam := s[p];
              s[p] := s[q];
              s[q] := tam;
          end;
end;
begin
    assign(input,'xau11.inp');reset(input);
    assign(output,'xau11.out');rewrite(output);
    readln(n);
    for i := 1 to n do
      begin
          read(a[i]);
          str(a[i], s[i]);
      end;
    bbs;
    s0 := '';
    for i := 1 to n do s0 := s0 + s[i];
    writeln(s0);
    close(input);close(output);
end.