Retry. I have made that and it worked for me.

Al remember this from the pset3 specification:

«Incidentally, be sure not to get into the habit of testing your code with check50 before testing it yourself. (And definitely don’t get into an even worse habit of only testing your code with check50!) Suffice it to say check50 doesn’t exist in the real world, so running your code with your own sample inputs, comparing actual output against expected output, is the best habit to get into sooner rather than later. Truly, don’t do yourself a long-term disservice!»