mixster

program New;
function InsertBetweenMix(str, insB, insA, frm, unt: string): string;
var
  fI, uI: Integer;
begin
  repeat
    fI := PosEx(frm, str, uI + 1);
    uI := PosEx(unt, str, fI + 1);
    if fI <= 0 then
      Break;
    if uI <= 0 then
      uI := Length(str);
    Insert(insB, str, fI);
    IncEx(uI, Length(insB) + 1);
    Insert(insA, str, uI);
    IncEx(uI, Length(insA));
  until false;
  Result := str;
end;

begin
  Writeln(InsertBetweenMix('Hello {world}, how are you {the world}?', '[', ']', '{', '}'));
end.