type textFile = monitor;
var N, actualN = 0 : Integer;
var x : condition;
var temp : Integer;

procedure entry ENTER
begin
  when actualN < N
    x.wait();
  actualN := actualN + i.ID;
end;

procedure entry LEAVE
begin
  actualN := actualN - i.ID;
  x.signal();
end;


procedure process
begin
  textFile.ENTER;

  // WORK ON FILE

  textFile.LEAVE;
end;