hi there community, i want to ask what do the constraints input:input.txt output:output.txt refer to? (i was solving problem 253A i took input as cin (as input is generally taken in C++) but when i submitted it showed TLE in first test case, but it was showing 0 sec in custom testing) please tell me what is input:input.txt output:output.txt?

hi there community. i have problem in finding the problems i left undone(submitted wrong) since i was unable to solve them then, but now i think i am able to give those problem another shot but its quite a difficult task to find each problem left undone in that submission columns. is there any easy possible way of finding those problems?