#include <cstdio>
#include <bits/stdc++.h>
long long int ncr ( int n, int r) {
    if(r==0) return (long long)1;
    else if(n==r) return (long long)1;
    else return (long long)ncr(n-1,r-1)+ncr(n-1,r);
}
using namespace std;
int main () {
    map <int, int> xx, yy;
    pair <int, int> xxx;
    map < pair <int, int> , int> paira;
    int n, x, y, i;
    scanf("%d", &n);
    int ara[n][2];
    for (i=0; i<n; i++) {
        scanf("%d %d", &x, &y);
        xx[x]++;
        yy[y]++;
        xxx.first = x;
        xxx.second = y;
        paira[xxx]++;
        ara[i][0] = x;
        ara[i][1] = y;
    }
    long long int one=0, two=0, three=0, ans = 0;

    for (i=0; i<n; i++) {
        if (xx[ara[i][0]] > 1) {
            one+= ncr(xx[ara[i][0]], 2);
            xx[ara[i][0]] = 0;
        }
        if (yy[ara[i][1]] > 1) {
            two += ncr (yy[ara[i][1]], 2);
            yy [ara[i][1]] = 0;
        }
        xxx.first = ara[i][0];
        xxx.second = ara[i][1];
        if (paira[xxx] > 1) {
            three += ncr (paira[xxx], 2);
            paira[xxx]=0;
        }
    }

    printf("%I64d\n", one+two - three);
    return 0;
}