#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, x, y;
  map<long long, long long> mx, my;
  map<tuple<long long, long long>, long long> mt;
  scanf("%lld", &n);
  for (int i = 0; i < n; i++) {
    scanf("%lld%lld", &x, &y);
    tuple<long long, long long> a = make_tuple(x, y);
    mx[x]++;
    my[y]++;
    mt[a]++;
  }
  long long ans = 0;
  for (auto a : mx) {
    long long b = a.second;
    ans += b * (b - 1) / 2;
  }
  for (auto a : my) {
    long long b = a.second;
    ans += b * (b - 1) / 2;
  }
  for (auto a : mt) {
    long long b = a.second;
    ans -= b * (b - 1) / 2;
  }
  printf("%lld\n", ans);
}
