uses crt;
var s1,s2: string;

procedure MergeStr(var s1: string; var s2: string);
var i, l: byte;
begin
    l := byte(s1[0]);
    for i := 1 to byte(s2[0]) do begin
        s1[i+l] := s2[i];
        //Writeln(s2[i]);
    end;
    s1[0] := char(i+l-1);
end;

begin
    s1 := 'ABC';
    s2 := 'DEFGHIJ';
    MergeStr(s1, s2);
    Writeln(s1);
    ReadKey;
end.