func_code_string: #include <bits/stdc++.h>   using namespace std;   int a, b, c;   int main() {     cin >> a >> b >> c;     int i, s = 0;     for (i = 1; i <= a - 1; i++) s += i;     cout << (c + a - 1) * (b + a - 1) - 2 * s;   }   