### Reinventing the wheel

Do not reinvent the wheel

### Coprimes

#### Coprimes [ACM ICPC Regionals 2014 - Asia Anshan]

Given a sequence a of n integers ($n ≤ 10^5$) where ($a_i ≤ 10^5$), find the number of triplets (x, y, z) such that they are either pairwise coprime, or pairwise not coprime, feel free to check the problem statement for more explanation.

### Mirror trap

Ever met a geometry problem that doesn’t have much to do with geometry ? this is the problem we want to discuss today, Mirror trap from the 15th Polish Olympiad in Informatics.

### Solvable sat

Boolean satisfiability problem (SAT) is a problem where we are given a boolean expression, asking whether there exists an assignment of variables that makes the expression true.