#include <bits/stdc++.h>
using namespace std;
map<pair<long long, long long>, long long> O;
map<pair<long long, long long>, long long>::iterator oit;
map<long long, long long> X, Y;
map<long long, long long>::iterator it;
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    double x, y;
    cin >> x >> y;
    O[make_pair(x, y)]++;
    X[x]++;
    Y[y]++;
  }
  long long cnt = 0;
  for (it = X.begin(); it != X.end(); ++it)
    if (it->second > 1) cnt += (it->second - 1) * (it->second) / 2;
  for (it = Y.begin(); it != Y.end(); ++it)
    if (it->second > 1) cnt += (it->second - 1) * (it->second) / 2;
  for (oit = O.begin(); oit != O.end(); ++oit)
    if (oit->second > 1) cnt -= (oit->second - 1) * (oit->second) / 2;
  cout << cnt << endl;
  return 0;
}
