/*
task:man
lang:c++
*/
int n,a[2500][2500];
#include<iostream>
using namespace std;
int main()
{
    cin>>n;
    int c,b,i,p=0,j;
    for(i=1;i<=n;i++){
                      cin>>c>>b;
                      if(a[c][0]==0||a[b][0]==0){p++;a[c][b]=1;
                                                   a[b][c]=1;a[c][0]++;a[b][0]++;}
                      else {for(j=0;j<=2500;j++)if(a[j][b]==1&&a[j][c]==1){break;}
                      if(j==2501){p++;a[c][b]=1;
                                                  a[b][c]=1;a[c][0]++;a[b][0]++;}}
                      }
    cout<<p<<"\n";                                          
    return 0;
}   
