var
     text: string;
     flag: boolean;
     k, i: integer;

begin
     readln(text);
     flag := true;
     text := text + ' ';
     while flag do
     begin
          k := 1;
          for i := 1 to length(text) - 1 do
          begin
               if (text[i + 1] = ' ') then break;
               if (text[i] = text[i + 1]) then begin
                    delete(text, i, 2);
                    k := 0;
                    break;
               end;
          end;
          if k = 0 then flag := true else flag := false;
     end;
     for i := 1 to length(text) - 1 do write(text[i]);
end.

Edited by author 26.02.2014 01:33

Edited by author 26.02.2014 01:34