Heidi has finally found the mythical Tree of Life – a legendary combinatorial structure which is said to contain a prophecy crucially needed to defeat the undead armies.

On the surface, the Tree of Life is just a regular undirected tree well-known from computer science. This means that it is a collection of n points (called vertices), some of which are connected using n - 1 line segments (edges) so that each pair of vertices is connected by a path (a sequence of one or more edges).

To decipher the prophecy, Heidi needs to perform a number of steps. The first is counting the number of lifelines in the tree – these are paths of length 2, i.e., consisting of two edges. Help her!

Input

The first line of the input contains a single integer n – the number of vertices in the tree (1 ≤ n ≤ 10000). The vertices are labeled with the numbers from 1 to n. Then n - 1 lines follow, each describing one edge using two space-separated numbers a b – the labels of the vertices connected by the edge (1 ≤ a < b ≤ n). It is guaranteed that the input represents a tree.

Output

Print one integer – the number of lifelines in the tree.

Examples

Input

4
1 2
1 3
1 4


Output

3

Input

5
1 2
2 3
3 4
3 5


Output

4

Note

In the second sample, there are four lifelines: paths between vertices 1 and 3, 2 and 4, 2 and 5, and 4 and 5.
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
import java.util.*;
import java.io.*;
/**
 *
 * @author root
 */
public class F1 {
    
    public static void main(String args[]) throws IOException{
        BufferedReader br  = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int dp[] = new int[10000];
        dp[0] = 0;
        dp[1] = 0;
        dp[2] = 1;
        for(int i = 3;i<n;i++){
            dp[i] = dp[i-1]+i-1;
        }
        int edgeCount[] = new int[n];
        for(int i = 0;i<n-1;i++){
            String line = br.readLine();
            String tokens[] = line.split(" ");
            int a = Integer.parseInt(tokens[0]);
            int b = Integer.parseInt(tokens[1]);
            edgeCount[a-1]++;
            edgeCount[b-1]++;
        }
        int ans = 0;
        for(int i = 0;i<n;i++){
            ans+=dp[edgeCount[i]];
        }
        System.out.println(ans);
    }
}
