/*
TASK:man
LANG:C++
*/
#include<iostream>
using namespace std;
int main()
{
    int M,a,b,c[15000],d,max=1,p,s[15000],br=0,t;
    cin>>M;
    for(int j=0;j<=15000;j++)
    c[j]=j;
    for (int i=0;i<=M-1;i++)
    cin>>a>>b;
    if (a>b)
    {
             d=a;
             a=b;
             b=d;
             }
             if (b>max)
             max=b;
             if (c[a]==a)
             c[a]=b;
             else
             {
             p=c[a];
             c[a]=b;
                  for(int k=0;k<=15000;k++)
                  if (c[k]==p)
                   c[k]=b;
                  }
                  if (c[0]!=0) 
                  {
                  br=1;
                  if (c[1]!=c[0]) br=2;
                  }
                  else br=1;
                  for (int r=2;r<=max;r++)
                  {for(int  v=r-1;v>=0;v--)
                  {if (c[r]==c[v])t=1;
                  }
                  if(t!=1) br++;
                  }
                  cout<<br;
                  cout<<endl;
                  return 0;
                  }
                  
                  
                            
                   
                  
    
    
    
    
    
    
    
