import java.util.*;
   import java.io.*;

    class Dwite4
   {
   
   
   
      static int [][]dist; 
      static int infinity = 9999;
   	
       public static void main (String [] args) throws IOException
      {
      
         Scanner in = new Scanner (new File ("DATA4.txt"));
         PrintWriter out = new PrintWriter (new File ("OUT4.txt"));
      
      
         for (int x = 0; x < 5; x++)
         {
         
            dist = new int[101][101];
            for (int i = 0; i < 101; i++)
               for (int j = 0; j < 101; j++)
                  dist [i][j] = infinity;
         
            int temp = in.nextInt();
            for (int i = 0; i < temp; i++)
               dist [in.nextInt()][in.nextInt()] = 1;
           
         
         
                    
            for (int j = 0; j < 101; j++)
               for (int k = 0; k < 101; k++)
                  for (int m = 0; m < 101; m++)
                     if (dist[k][j]+dist[j][m]<dist[k][m])
                        dist[k][m]=dist[k][j]+dist[j][m];
         
            int sum = 0;
            for (int i = 0; i < 101; i++)
               for (int j = 0; j < 101; j++)
                  if (dist [1][i] == dist [1][j] && dist [i][j] == 1)
                     sum ++;
                  
         
         
            out.println (sum);
         }
         out.close();
      
      }
      
   }