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 first = in.nextInt();
            int sec = in.nextInt();
            boolean found = true,
                found1 = true;
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
                if(x != first)  found = false;
                if(y != sec) found1 = false;
        }
            System.out.println((found || found1)? "YES" : "NO");
    }
}