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.

import java.util.Scanner;

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author evgen
 */
public class class11 {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
    int n=in.nextInt();int s=0;
    short[][] ar=new short[n+1][n+1];int y=n-1;
    while(y>0){
    int a=in.nextInt();int b=in.nextInt();
        ar[a][b]=1;ar[b][a]=1;
y--;    }
      
        
            for(int i=1;i<=n;i++){
                for(int j=1;j<=n;j++){
        if(ar[i][j]==1){
        int g=0;
        for(int k=1;k<=n;k++){if(ar[j][k]==1){g++;}}
        s=s+g-1;
        }  
            }}
        System.out.println(s/2);
    }}