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
class Uf:
    def __init__(self, N):
        self.p = list(range(N))
        self.rank = [0] * N
        self.size = [1] * N

    def root(self, x):
        if self.p[x] != x:
            self.p[x] = self.root(self.p[x])

        return self.p[x]

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

    def unite(self, x, y):
        u = self.root(x)
        v = self.root(y)

        if u == v: return

        if self.rank[u] < self.rank[v]:
            self.p[u] = v
            self.size[v] += self.size[u]
            self.size[u] = 0
        else:
            self.p[v] = u
            self.size[u] += self.size[v]
            self.size[v] = 0

            if self.rank[u] == self.rank[v]:
                self.rank[u] += 1

    def count(self, x):
        return self.size[self.root(x)]

from operator import itemgetter
from collections import defaultdict
from itertools import groupby
N = int(input())
XYI = []
for i in range(N):
    x, y = map(int, input().split())
    XYI.append([x, y, i])
XYx = sorted(XYI, key=itemgetter(0))
XYy = sorted(XYI, key=itemgetter(1))

uf = Uf(N)
px = py = -1
for x, y, i in XYx:
    if px==x:
        uf.unite(i, pi)
    px, pi = x, i
for x, y, i in XYy:
    if py==y:
        uf.unite(i, pi)
    py, pi = y, i
ddx = defaultdict(set)
ddy = defaultdict(set)
for x, y, i in XYI:
    ddx[uf.root(i)].add(x)
    ddy[uf.root(i)].add(y)
ans = 0
for i in range(N):
    if i==uf.root(i):
        ans += len(ddx[i]) * len(ddy[i])
print(ans - N)
