Petya and Strings https://codeforces.com/problemset/problem/112/A
Helpful Math https://codeforces.com/problemset/problem/339/A
Word Capitalization https://codeforces.com/problemset/problem/281/A
simulation of all possiblites for a bishob in a free board link https://github.com/hossamAhmedSalah/problemSolving/blob/main/ps_with_python/allBishopNumOfMoves.py