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 collections import defaultdict, deque, Counter
from heapq import heappush, heappop, heapify
import math
from bisect import bisect_left, bisect_right
import random
from itertools import permutations, accumulate, combinations
import sys
import string



INF = float('inf')
def LI(): return list(map(int, sys.stdin.readline().split()))
def I(): return int(sys.stdin.readline())
def LS(): return sys.stdin.readline().split()
def S(): return sys.stdin.readline().strip()
def IR(n): return [I() for i in range(n)]
def LIR(n): return [LI() for i in range(n)]
def SR(n): return [S() for i in range(n)]
def LSR(n): return [LS() for i in range(n)]
def SRL(n): return [list(S()) for i in range(n)]
def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]
mod = 10 ** 9 + 7


class UnionFind:
    def __init__(self, n):
        # 負  : 根であることを示す。絶対値はランクを示す
        # 非負: 根でないことを示す。値は親を示す
        self.table = [-1] * n
        self.size = [1] * n
        self.group_num = n

    def root(self, x):
        if self.table[x] < 0:
            return x
        else:
            self.table[x] = self.root(self.table[x])
            return self.table[x]

    def is_same(self, x, y):
        return self.root(x) == self.root(y)

    def get_size(self, x):
        r = self.root(x)
        return self.size[r]

    def union(self, x, y):
        r1 = self.root(x)
        r2 = self.root(y)
        if r1 == r2:
            return
        # ランクの取得
        d1 = self.table[r1]
        d2 = self.table[r2]
        if d1 <= d2:
            self.table[r2] = r1
            self.size[r1] += self.size[r2]
            if d1 == d2:
                self.table[r1] -= 1
        else:
            self.table[r1] = r2
            self.size[r2] += self.size[r1]
        self.group_num -= 1



n = I()
U = UnionFind(10 ** 5 * 2)
for i in range(n):
    x, y = LI()
    U.union(x - 1, y + 10 ** 5 - 1)



X = [0] * 10 ** 5 * 2
Y = [0] * 10 ** 5 * 2
for x in range(10 ** 5):
    X[U.root(x)] += 1
for y in range(10 ** 5, 10 ** 5 * 2):
    Y[U.root(y)] += 1


ret = 0
for j in range(10 ** 5 * 2):
    ret += X[j] * Y[j]


print(ret - n)