#include <bits/stdc++.h>
using namespace std;
map<int, long long> x, y;
map<pair<int, int>, long long> xy;
int main() {
  int n;
  cin >> n;
  while (n--) {
    int xx, yy;
    cin >> xx >> yy;
    x[xx]++;
    y[yy]++;
    xy[make_pair(xx, yy)]++;
  }
  long long ans = 0;
  for (auto i : x) {
    ans += i.second * (i.second - 1) / 2;
  }
  for (auto i : y) {
    ans += i.second * (i.second - 1) / 2;
  }
  for (auto i : xy) {
    ans -= i.second * (i.second - 1) / 2;
  }
  cout << ans << endl;
}
