method1

import java.io.*;
import java.util.*;
public class IEEE {

    public static void main(String[] args) throws IOException {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int x,y;
        //method 1(using the 2d array);
        int board[][]=new int [1001][1001];

        //filling the board with pieces
        for(int i=0;i<n;i++){
            x=sc.nextInt();
            y=sc.nextInt();
            board[x][y]=1;
        }
        //_______end of the input________\\

        int sum =0;//number of attacks
        int counter=0;//number of pieces in every row

        //loop for the rows:
        for(int i=1;i<1001;i++){
            for(int j=1;j<1001;j++){
                if(board[i][j]==1)counter++;
            }
            sum+=(counter*(counter-1))/2;//adding the number of attack
            counter=0;//reset the value to zero to start a new row
        }
        //loop for the colums
        for(int i=1;i<1001;i++){
            for(int j=1;j<1001;j++){
                if(board[j][i]==1)counter++;
            }
            sum+=(counter*(counter-1))/2;
            counter=0;
        }
        System.out.println(sum);
    }

}