Watchmen are in a danger and Doctor Manhattan together with his friend Daniel Dreiberg should warn them as soon as possible. There are n watchmen on a plane, the i-th watchman is located at point (xi, yi).

They need to arrange a plan, but there are some difficulties on their way. As you know, Doctor Manhattan considers the distance between watchmen i and j to be |xi - xj| + |yi - yj|. Daniel, as an ordinary person, calculates the distance using the formula .

The success of the operation relies on the number of pairs (i, j) (1 ≤ i < j ≤ n), such that the distance between watchman i and watchmen j calculated by Doctor Manhattan is equal to the distance between them calculated by Daniel. You were asked to compute the number of such pairs.

The first line of the input contains the single integer n (1 ≤ n ≤ 200 000) — the number of watchmen.

Each of the following n lines contains two integers xi and yi (|xi|, |yi| ≤ 109).

Some positions may coincide.

Print the number of pairs of watchmen such that the distance between them calculated by Doctor Manhattan is equal to the distance calculated by Daniel.

In the first sample, the distance between watchman 1 and watchman 2 is equal to |1 - 7| + |1 - 5| = 10 for Doctor Manhattan and  for Daniel. For pairs (1, 1), (1, 5) and (7, 5), (1, 5) Doctor Manhattan and Daniel will calculate the same distances.

思路：结果就是计算同一横坐标、纵坐标上有多少点，再减去可能重复的数量（用map，pair存一下）

#include <iostream>

#include <stdio.h>

#include <algorithm>

#include <cstring>

#include <cmath>

#include <stack>

#include <map>

using namespace std;

#define ll long long

ll a,b;

map<ll,ll> mp1;

map<ll,ll> mp2;

map< pair<ll,ll>,ll> mp;

int main()

{

    int n,m;

    while(scanf("%d",&n)!=EOF){

        ll ans=,num=;

        mp1.clear();

        mp2.clear();

        mp.clear();

        for(int i=;i<=n;i++){

            scanf("%lld%lld",&a,&b);

            num+=mp[make_pair(a,b)];

            mp[make_pair(a,b)]++;

            if(mp1.find(a)==mp1.end())

                mp1[a]=;

            else {

                ans+=mp1[a];

                mp1[a]++;

            }

            if(mp2.find(b)==mp2.end())

                mp2[b]=;

            else {

                ans+=mp2[b];

                mp2[b]++;

            }

        }

        printf("%lld",(ll)ans-num);

    }

    return ;

}