#include <iostream>
using namespace std;

const int M = 1000000007;
long long modexp(int x, long long e, int m) {
    long long ans = 1, p = x % m;
    while (e > 0) {
        if (e % 2 != 0) ans = (ans * p) % m;
        p = (p * p) % m;
        e >>= 1;
    }
    return ans;
}

int main() {
    long long n, k; cin >> n >> k;
    k %= M;
    cout << ((modexp(((k + 1) * (k + 2) / 2 - 1) % M, n, M)
              - modexp(k * (k + 1) / 2 % M, n, M)) % M + M) % M << endl;
}