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
import sys,os,math
from collections import Counter, defaultdict, deque, OrderedDict
import bisect
from sys import stdin, stdout
from itertools import repeat
import Queue


# sys.stdin = open('input')
# n, k = map(int, raw_input().split())
# da = map(int, raw_input().split())
# db = map(int, raw_input().split())


def main():
    n = map(int, raw_input().split())[0]
    G = defaultdict(list)
    bfs = []
    for i in range(n):
        a, b = map(int, raw_input().split())
        b += 100000
        G[a].append(b)
        G[b].append(a)
        bfs.append(a)

    vs = set()
    ans = 0
    for i in bfs:
        if i in vs:
            continue
        x, y = 0, 0
        t = 0
        vs.add(i)
        q = deque()
        q.append(i)
        while q:
            now = q.popleft()
            if now > 100000:
                y += 1
            else:
                x += 1
            for adj in G[now]:
                t += 1
                if adj not in vs:
                    # print adj
                    vs.add(adj)
                    q.append(adj)
        # print x, y, t/2
        ans += x*y - t/2
    print ans




main()
