program sdf;
var i,j,k,l,n,m,max:longint;
    a:array[1..58]of longint;
    str,str1:ansistring;
begin
    //while not eof do begin
        readln(str);
        for i:=1 to length(str) do
          inc(a[ord(str[i])-64]);
        max:=0;
        for i:=1 to 58 do
        if max<a[i] then
        max:=a[i];
        for i:=1 to length(str) do
        if a[ord(str[i])-64]=max then begin
            write(str[i]);
            a[ord(str[i])-64]:=-1;
        end;
        writeln;
    //end;
end.

May be all elements of array a should be equals by zero?

Edited by author 22.09.2011 18:26

Edited by author 22.09.2011 18:27

test for you: "tebidoghtebidoh"