#include "bits/stdc++.h" using namespace std; typedef long long ll; const int INF = (1<<30); const ll INFLL = (1ll<<60); const ll MOD = (ll)(1e9+7); #define l_ength size void mul_mod(ll& a, ll b){ a *= b; a %= MOD; } void add_mod(ll& a, ll b){ a = (a> n; for(i=0; i> y[i]; s += y[i]; y[i] *= (n-1); } for(i=0; i