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();
        boolean h = true, v = true;
        int x = in.nextInt();
        int y = in.nextInt();
        for(int a0 = 1; a0 < n; a0++){
            if(in.nextInt()!=x)     h = false;
            if(in.nextInt()!=y)     v = false;
        }
        if(!h && !v)    System.out.println("NO");
        else            System.out.println("YES");
    }
}