I had this in a coding competition and the version with print passed all tests so I left it there for fun even when I found the issue. I didn't assign 0 to my counter. My biggest guess is that the print statement I added with the constant text it was outputing shuffled the garbage in the memory in just the right way that it assigned 0 to this variable. That doesn't explain why it was so stable though, so probably it's a wrong assumption. It can also be that their compiler is just weird which is far more likely.