import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

public class Solution {

    public static void main(String[] args) {
        
		
		Scanner s = new Scanner(System.in);
		int t = s.nextInt();
		int n= t;
		Map<Integer,Integer> m = new HashMap<Integer,Integer>();
		Map<Integer,Integer> m1 = new HashMap<Integer,Integer>();
		while(t-->0){
			int a = s.nextInt();
			int b = s.nextInt();
			if(m.containsKey(a))
				m.put(a, m.get(a)+1);
			else
				m.put(a, 1);
			
			if(m1.containsKey(b))
				m1.put(b, m1.get(b)+1);
			else
				m1.put(b, 1);
		}
		
		for(Entry<Integer,Integer> e : m.entrySet())
		{
			if(e.getValue().equals(n)){
				System.out.println("YES");
				return;
				}
			
		}
		
		for(Entry<Integer,Integer> e : m1.entrySet())
		{
			if(e.getValue().equals(n)){
				System.out.println("YES");
				return;
			}
		}
		
		System.out.println("NO");

	
    }
}