I was solving 408B and it was easy. I submitted the code and I get WA in test 15. Then I have revised the code and changed the arrays' size from 1000 to 1005 and it worked! In the problem maximum length of both strings is 1000. why did that happen? first submission WA on test 15 : 28983405. second submission Accepted : 28983523

please do not down vote before telling me what is the wrong in my question

UPD: Thanks to fresher96 for his explanation

UPD:scanf format string article in Wikipedia mentions that:

%s : Scan a character string. The scan terminates at whitespace. A null character is stored at the end of the string, which means that the buffer supplied must be at least one character longer than the specified input length.