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
#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

std::vector<std::vector<LL>>G(212345);
std::vector<bool>vis(212345, false);

std::pair<LL, LL> dfs(LL v)
{
	if (vis[v]) return { 0,0 };
	vis[v] = true;
	std::pair<LL, LL>res;
	if (v <= 100000) res.first = 1;
	else res.second = 1;
	for (LL u : G[v])
	{
		auto temp = dfs(u);
		res.first += temp.first;
		res.second += temp.second;
	}
	return res;
}

int main()
{
	LL N;
	in >> N;
	std::vector<LL>x(N), y(N);
	rep(i, N) in >> x[i] >> y[i];

	LL ans = 0;
	rep(i, N)
	{
		y[i] += 100000;
		G[x[i]].push_back(y[i]);
		G[y[i]].push_back(x[i]);
	}
	for (LL i = 1; i <= 200000; ++i)
	{
		auto res = dfs(i);
		ans += res.first * res.second;
	}
	ans -= N;

	out << ans << std::endl;
}
