#include <bits/stdc++.h>   using namespace std;   long long a, b;   int main() {     cin >> a >> b;     long long ans = (b * (b - 1)) / 2;     ans %= 1000000007;     ans =         (a * ans + ((b * ans) % 1000000007) * ((a * (a + 1) / 2) % 1000000007)) %         1000000007;     cout << ans;     return 0;   }   