/*
TASK: man
LANG: C++
*/
//Rumen Hristov Hristov

#include <stdio.h>

#define MAX 15001

int m;
bool a[ MAX ][ MAX ];

void solve()
{
    int i,j;
    int x,y;
    int ans;
    int n;
    
    ans = 0;
    n = 0;
    
    scanf ("%d",&m);
    
    for (i=1;i<=m;i++)
    {
        scanf ("%d%d",&x,&y);
        
        if ( x > n ) n = x;
        if ( y > n ) n = y;

        for (j=0;j<=n;j++)
        {
            if ( a[x][j] == true && a[j][y] == true )
            {
                break;
            }
        }
        
        if ( j == n+1 )
        {
            a[x][y] = a[y][x] = 1;
            ans++;
        }
    }
    
    printf ("%d\n",ans);
}

int main()
{
    solve();
    
    return 0;
}
