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
import sys
sys.setrecursionlimit(10**9)
n = int(input())
data = []
for i in range(n):
    data.append(list(map(int, input().split())))
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

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

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

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

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())
unionfind = UnionFind(n)
x_d = defaultdict(set)
y_d = defaultdict(set)
for i in range(n):
    x_d[data[i][0]].add(i)
    y_d[data[i][1]].add(i)

for i in range(n):
    x, y = data[i]
    if len(x_d[x]) > 1 and len(y_d[y]) > 1:
        for j in x_d[x]:
            unionfind.union(i, j)
        for j in y_d[y]:
            unionfind.union(i, j)

point = [[] for i in range(n)]
for i in range(n):
    if unionfind.size(i) <= 2:
        continue
    else:
        point[unionfind.find(i)].append(i)
ans = 0
for i in range(n):
    if len(point[i]) > 2 :
        x_s = set()
        y_s = set()
        for j in point[i]:
            x, y = data[j]
            x_s.add(x)
            y_s.add(y)
        ans += len(x_s) * len(y_s) - len(point[i])
print(ans)
