#include <bits/stdc++.h>
using namespace std;
map<long long, long long> mp1, mp2;
long long n, x, yy, c;
vector<pair<int, int>> v;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x >> yy;
    v.push_back({x, yy});
    mp1[x + yy]++;
    mp2[x - yy]++;
  }
  for (int i = 0; i < n; i++) {
    x = v[i].first;
    yy = v[i].second;
    c += mp1[x + yy];
    c += mp2[x - yy];
    c -= 2;
  }
  cout << c / 2 << endl;
  return 0;
}
