func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, i, a, b, s = 0;     cin >> n;     map<int, int> m1, m2;     for (i = 1; i < n + 1; ++i) {       int a, b;       cin >> a >> b;       s += m1[a + b]++;       s += m2[a - b]++;     }     cout << s;   }   