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 java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    Node[] nodes = new Node[200_001];
    for (int i = 0; i < 200_001; i++) nodes[i] = new Node(i);
    int N = scanner.nextInt();
    for (int i = 0; i < N; i++) {
      int x = scanner.nextInt();
      int y = scanner.nextInt() + 100_000;
      nodes[x].adjacents.add(nodes[y]);
      nodes[y].adjacents.add(nodes[x]);
    }

    boolean[] visited = new boolean[200_001];
    long res = 0;
    for (int i = 0; i < 200_001; i++) {
      if (!visited[i]) {
        Result result = new Result();
        dfs(nodes[i], visited, result);
        res += (long) result.nx * result.ny - result.m / 2;
      }
    }
    System.out.println(res);
  }

  private static void dfs(Node node, boolean[] visited, Result result) {
    visited[node.id] = true;
    if (node.id <= 100_000) result.nx++;
    else result.ny++;
    for (Node n : node.adjacents) {
      result.m++;
      if (!visited[n.id]) {
        dfs(n, visited, result);
      }
    }
  }

  private static class Result {
    int nx;
    int ny;
    int m;
  }

  private static class Node {
    private final int id;
    private List<Node> adjacents = new ArrayList<>();
    public Node(int id) {
      this.id = id;
    }
  }
}
