I am dumbfounded whenever i face a problem which requires coming out with a formula on your own! especially when it's related to maths. Like the Your text to link here... 1511B - GCD Length. I started by reading the problem and re-reading and doing that in a loop and even the slightest hint of the answer did not start materializing inside my head. Tips on tackling that types of questions?..

ps:- i learned about gcd, co-prime etc but still it's literally of no help to me and i like to think that I'm not that bad at general maths either!!

Any tips or tricks for facing those kind of problems headon is appreciated!