import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.StringTokenizer;


public class Q5 {
	public static void main(String[] args) throws IOException{
		int[] xCoord = new int[100];
		int[] yCoord = new int[100];
		int number,yValue,xValue;

		BufferedReader input = new BufferedReader(new FileReader("DATA5.txt"));
		PrintWriter output = new PrintWriter("OUT5.txt");
		
		for(int times = 1; times < 5; times++){
			int counter = 1;
			number = Integer.parseInt(input.readLine());
			for(int i = 0; i < number; i++){	
				StringTokenizer token = new StringTokenizer (input.readLine());					
				xCoord[i] = Integer.parseInt(token.nextToken());
				yCoord[i] = Integer.parseInt(token.nextToken());
			}
			
			yValue = yCoord[0];
			
			while (yValue != xCoord[0]){		
				
				for (int i = 0; i < number ; i ++){
					if (xCoord[i] == yValue){
					xValue = xCoord[i];
					yValue = yCoord[i];
					counter++;
					if (number == 5){
					
					System.out.println(xValue);
					
					}
					
					if ( i == number )
						break;
					}
				}
			
			}
			
	
			output.println(counter);	
		}		
			
		input.close();
		output.close();
		System.exit(0);
	}
}