func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int a, n;     cin >> a >> n;     int tilln = (1LL * n * (n - 1) / 2) % 1000000007,         tilla = (1LL * a * (a + 1) / 2) % 1000000007;     cout << ((((((1LL * tilln) % 1000000007) * tilla) % 1000000007) * n) %                  1000000007 +              (1LL * a * tilln) % 1000000007) %                 1000000007          << endl;     return 0;   }   