#include <iostream> #include <vector> using namespace std; const int MOD = 1000000007; long long modPow(long long a, long long p){ if(p == 0) return 1; auto res = modPow(a, p/2); res = (res*res)%MOD; if(p%2) res = (res*a)%MOD; return res; } int main(){ const int maxSize = 200001; vector<long long> inv(maxSize); vector<long long> fact(maxSize); vector<long long> factInv(maxSize); for(int i=0;i<2;i++) inv[i] = fact[i] = factInv[i] = 1; for(int i=2;i<maxSize;i++){ inv[i] = inv[MOD % i] * (MOD - MOD / i) % MOD; fact[i] = fact[i-1] * i % MOD; factInv[i] = factInv[i-1] * inv[i] % MOD; } auto comb = [&](int n, int r){ if(n < r || r < 0) return 0LL; return fact[n] * factInv[n-r] % MOD * factInv[r] % MOD; }; long long N, K; while(cin >> N >> K){ long long res = 0; long long s = K%MOD * ((K+1)%MOD) % MOD * inv[2] % MOD; for(int i=0;i<N;i++){ long long sp = modPow(s, i); sp = (sp * comb(N, i)) % MOD; sp = (sp * modPow(K%MOD, N-i)) % MOD; res = (res + sp) % MOD; } cout << res << endl; } }