Should really be attached to the article but anyway. You don't see 13 and José does. What does this tell you?
I'll let you work this one out for yourself but I'll pose a few relevant questions.
How many consoles/terminals is this program attached to?
Was the console you're using around before multithreading?
Given a choice of getting
as output from your program which would your choose?
Now I guess you understand the problem. The reall interesting part is what's the best way to solve it given you can't rewrite the Console program, or even if you could?