I was solving questions for practice and eventually came across this problem A of CFR 347 div2 . In this question the GCD of two numbers 100 and 100000 is 100. But when i submit my solution it shows 100 is wrong answer and right answer is 1. Probably i am unable to understand the question. Can anyone explain me the problem clearly?

Here is the link to the problem. https://mirror.codeforces.com/contest/664/problem/A