Codeforces1807A. Plus or Minus(Div 4)
https://freecodecenter.com/codeforces1807a-plus-or-minus/
Codeforces 1807 B. Grab the Candies solution
https://freecodecenter.com/grab-the-candies-solution/
Codeforces All problem solution
https://freecodecenter.com/online-judge-solutions/codeforces-problem-solution/