PROGRAM procedure_calling_a_procedure;

PROCEDURE one;
BEGIN
  WRITELN('This is procedure one');
END;

PROCEDURE two;
BEGIN
  one;
  WRITELN('This is procedure two');
END;

PROCEDURE three;
BEGIN
  two;
  WRITELN('This is procedure three');
END;

BEGIN  (* main program *)
  one;
  WRITELN;
  two;
  WRITELN;
  three;
END. (* of main program *)