#include #define rep(i,n) for(int i=0;i<(n);i++) using namespace std; bool is_prime(long long a){ if(a%2==0) return a==2; for(long long i=3;i*i<=a;i+=2) if(a%i==0) return false; return a!=1; } vector divisors(long long a){ vector res; for(long long i=1;i*i<=a;i++) if(a%i==0) { res.emplace_back(i); if(i*i