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
from itertools import*
from math import*
from collections import*
from heapq import*
from bisect import bisect_left,bisect_right
from copy import deepcopy
inf = float("inf")
mod = 10**9+7
from functools import reduce
import sys
sys.setrecursionlimit(10**7)

class UnionFind():
    def __init__(self, N):
        self.rank = [0] * N
        self.par = [i for i in range(N)]
        self.counter = [1] * N

    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x != y:
            z = self.counter[x] + self.counter[y]
            self.counter[x], self.counter[y] = z, z
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1

    def size(self, x):
        x = self.find(x)
        return self.counter[x]

    def same(self, x, y):
        return self.find(x) == self.find(y)

N = int(input())
uf = UnionFind(N)
x_dict={}
y_dict={}

xy = []
for i in range(N):
    x,y = map(int,input().split())
    if x in x_dict:
        uf.unite(i,x_dict[x])
    else:
        x_dict[x]=i
    if y in y_dict:
        uf.unite(i,y_dict[y])
    else:
        y_dict[y]=i
    xy.append((x,y))
unite_dict={}
for i in range(N):
    ur = uf.find(i)
    unite_dict.setdefault(ur,[set(),set()])
    unite_dict[ur][0].add(xy[i][0])
    unite_dict[ur][1].add(xy[i][1])

p = 0
for k,v in unite_dict.items():
    p +=len(v[0])*len(v[1])
print(p-N)