#include<fstream.h>
ifstream in("trapez.in");
ofstream out("trapez.out");

int n,i,x[1010],y[1010],j,s,s2,qx,qy;
unsigned long p;
int main()
{

in>>n;
for(i=1; i<=n; i++)
	in>>x[i]>>y[i];


for(i=1; i<n; i++)
	{
	qx=0;qy=0;
	for(j=i+1;j<=n&&(!qx||!qy);j++)
		if(x[i]==x[j] && y[i]==y[j])
			{s++;s2++;qx=qy=1;}
		else if(x[i]==x[j])
			{s++;qx=1;}
		else if(y[i]==y[j])
			{s2++;qy=1;}

	}
p+=s*(s-1)/2;
p+=s2*(s2-1)/2;
out<<p;
return 0;
}