import java.util.*;
class Solution{
	public static void main(String args[]){
		Scanner in=new Scanner(System.in);
		int n=in.nextInt();
		int[][] p=new int[n][2];
		int repx=in.nextInt();
		int repy=in.nextInt();
		boolean line=true;
		for(int i=1;i<n;i++){
			p[i][0]=in.nextInt();
			p[i][1]=in.nextInt();
			if(p[i][0]!=repx && p[i][1]!=repy){	
				line=false;
				break;
			}	
		}
		if(line){
			System.out.println("YES");
		}
		else{
			System.out.println("NO");
		}
	}
}