There are N dots in a two-dimensional plane. The coordinates of the i-th dot are (x_i, y_i).

We will repeat the following operation as long as possible:

* Choose four integers a, b, c, d (a \neq c, b \neq d) such that there are dots at exactly three of the positions (a, b), (a, d), (c, b) and (c, d), and add a dot at the remaining position.



We can prove that we can only do this operation a finite number of times. Find the maximum number of times we can do the operation.

Constraints

* 1 \leq N \leq 10^5
* 1 \leq x_i, y_i \leq 10^5
* If i \neq j, x_i \neq x_j or y_i \neq y_j.
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
x_1 y_1
:
x_N y_N


Output

Print the maximum number of times we can do the operation.

Examples

Input

3
1 1
5 1
5 5


Output

1


Input

2
10 10
20 20


Output

0


Input

9
1 1
2 1
3 1
4 1
5 1
1 2
1 3
1 4
1 5


Output

16
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
#include<iostream>
using namespace std;
#define ll long long
#define re register
#define file(a) freopen(a".in","r",stdin);freopen(a".out","w",stdout)
#define MAX 100100
inline int gi(){
    int f=1,sum=0;char ch=getchar();
    while(ch>'9' || ch<'0'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0' && ch<='9'){sum=(sum<<3)+(sum<<1)+ch-'0';ch=getchar();}
    return f*sum;
}
int n,f[MAX<<1];
int getf(int x){return x==f[x]?x:f[x]=getf(f[x]);}
int sz1[MAX<<1],sz2[MAX<<1];
ll ans;
int main(){
    n=gi();
    for(int i=1;i<MAX+MAX;++i)f[i]=i;
    for(int i=1;i<=n;++i)
    {
        int u=gi(),v=gi();
        f[getf(u)]=getf(v+MAX);
    }
    for(int i=1;i<=MAX;++i)
        sz1[getf(i)]+=1;
    for(int i=MAX+1;i<MAX+MAX;++i)
        sz2[getf(i)]+=1;
    for(int i=1;i<MAX+MAX;++i)ans+=1ll*sz1[i]*sz2[i];
    cout<<ans-n<<endl;
    return 0;
}