#include <bits/stdc++.h>   using namespace std;   const int mo = 1e9 + 7;   int main() {     long long a, b, n;     while (cin >> a >> b) {       n = b - 1;       long long ans = 0;       for (int k = 1; k <= a; ++k) {         ans = (ans + (((((k * b) % mo) * ((n * (n + 1) / 2) % mo)) % mo +                        (n * (n + 1) / 2) % mo)) %                          mo) %               mo;       }       cout << ans % mo << endl;     }   }   