import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int a=0,b=0,ca=0,cb=0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if(a0==0){
                a = x;
                b = y;
            }
            
            if(x==a)
                ca++;
            if(y==b)
                cb++;
            
        }
        
        if(ca==n || cb==n){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}