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

public class five 
{
	
	public static void main(String[] args) throws IOException
	{
		BufferedReader bf = new BufferedReader(new FileReader("DATA5.txt"));
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("OUT5.txt")));
		
		for(int a = 0; a < 5; a++)
		{
			int size = Integer.parseInt(bf.readLine());
			int[] paths = new int[size + 1];
			
			for (int i = 0; i < size; i++)
			{
				StringTokenizer stk = new StringTokenizer(bf.readLine());
				int start = Integer.parseInt(stk.nextToken());
				int end = Integer.parseInt(stk.nextToken());
				
				paths[start] = end;
			}
			
			int count = 0;
			int index = 1;
			boolean looping = true;
			
			while (looping)
			{
				index = paths[index];
				if(index == 1)
					looping = false;
				count++;
			}
			
			out.println(count);
			
		}
		
		out.close();
		System.exit(0);
	}

}