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 tempx=in.nextInt();
        int tempy=in.nextInt();
        int countx=0;
        int county=0;
        for(int a0 = 0; a0 < n-1; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(tempx==x){
                countx++;
                tempx=x;
            }
            if(tempy==y){
                county++;
                tempy=y;
            }
            
        }
        if(countx==(n-1)|| county==(n-1)){
            System.out.println("YES");
        }else
            System.out.println("NO");
    }
}