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
def main():
    N = int(input())
    X, Y = {}, {}
    for _ in range(N):
        x, y = map(int, input().split())
        if x not in X:
            X[x] = set()
        X[x].add(y)
        if y not in Y:
            Y[y] = set()
        Y[y].add(x)
    r = 0
    while X:
        x, ys = X.popitem()
        tx = set([x])
        ty = set(ys)
        mx, my = set(), set(ys)
        while mx or my:
            while my:
                y = my.pop()
                mx |= Y.pop(y, set())
            tx |= mx
            while mx:
                x = mx.pop()
                my |= X.pop(x, set())
            ty |= my
        r += len(tx) * len(ty)
    return r - N

print(main())
