#include <bits/stdc++.h>

using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
typedef long long ll;
ll n,lines,ans;
struct point
{
    int x,y;
} v[1005];
bool comp1(point a, point b)
{
    return a.x<b.x;
}
bool comp2(point a, point b)
{
    return a.y<b.y;
}
int main()
{
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>v[i].x>>v[i].y;
    lines=0;
    sort(v+1,v+n+1,comp1);
    for(int i=2;i<=n;i++)
        if(v[i].x==v[i-1].x)
            lines++;
    ans+=(lines-1)*lines/2;

    lines=0;
    sort(v+1,v+n+1,comp2);
    for(int i=2;i<=n;i++)
        if(v[i].y==v[i-1].y)
            lines++;
    ans+=(lines-1)*lines/2;
    fout<<ans;
    return 0;
}