import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Friends {
	private ArrayList<int[]> values = new ArrayList<>();
	private Map<Integer, Integer> nodes;
	private Scanner in = new Scanner(System.in);

	private void getInput(){
		int n = in.nextInt();
		nodes = new HashMap<>(n);

		//Populate friends map
		for(int i = 0; i < n; i++){
			int n1 = in.nextInt();
			int n2 = in.nextInt();

			nodes.put(n1, n2);
		}

		//Test cases
		while(true){
			int n1 = in.nextInt();
			int n2 = in.nextInt();

			if(n1 == 0 && n2 == 0) break;

			values.add(new int[]{n1, n2});
		}
	}

	public int solve(int[] values){
		int root = nodes.get(values[0]);
		int target = nodes.get(values[1]);
		int n = root;
		int count = 0;

		while(true){
			n = nodes.get(n);

			if(n == root) return -1; //Not in friend's circle
			if(n == target) return count; //Is in friend's circle

			count++;
		}
	}

	private void outputAnswer(int answer){
		if(answer == -1) System.out.println("No");
		else System.out.println("Yes " + answer);
	}

	public static void main(String[] args){
		Friends f = new Friends();
		f.getInput();

		for(int[] i : f.values){
			int ans = f.solve(i);
			f.outputAnswer(ans);
		}
	}
}