PROGRAM PUSHPOP;

CONST LEVELS = 5;

VAR DEPTH : INTEGER;

PROCEDURE DIVE(VAR DEPTH : INTEGER);

BEGIN
  WRITELN('Push!');
  WRITELN('Our depth is now: ',DEPTH);
  DEPTH := DEPTH + 1;
  IF DEPTH <= LEVELS THEN DIVE(DEPTH);
  WRITELN('Pop!')
END;

BEGIN
  DEPTH := 1;
  DIVE(DEPTH)
END.