func_code_string: #include <bits/stdc++.h>   using namespace std;   const int max_n = 20010;   int lf[max_n];   int rf[max_n];   int main() {     long long sum = 0;     int n;     int x, y;     memset(lf, 0, sizeof(lf));     memset(rf, 0, sizeof(rf));     scanf( %d , &n);     for (int i = 0; i < n; ++i) {       scanf( %d%d , &x, &y);       ++lf[y - x + 1000];       ++rf[x + y];     }     for (int i = 0; i <= 2050; ++i) {       sum += (lf[i] * (lf[i] - 1)) / 2;     }     for (int i = 0; i <= 2050; ++i) {       sum += (rf[i] * (rf[i] - 1)) / 2;     }     printf( %I64d n , sum);     return 0;   }   