import java.util.Scanner;
import java.util.Stack;

public class Solution {

	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		Stack<Integer> x = new Stack<Integer>();
		Stack<Integer> y = new Stack<Integer>();
		for(int a0 = 0; a0 < n; a0++){
			x.add(in.nextInt());
			y.add(in.nextInt());
		}

		int countX = 0;
		int countY=0;
		while(!x.isEmpty()){
			int a = x.pop();
			if(!x.isEmpty()){
				if(a == x.peek()){
					countX++;
				}
			}
		}
		while(!y.isEmpty()){
			int a = y.pop();
			if(!y.isEmpty()){
				if(a == y.peek()){
					countY++;
				}
			}
		}
		if(countY==n-1 || countX==n-1){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}
}