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 x1 = in.nextInt();
        int y1 = in.nextInt();
        boolean p = false;
        boolean q = false;
        for(int a0 = 0; a0 < n-1; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(x != x1){
                p = true;
            }
            if(y!= y1){
                q = true;
            }
            if(p && q){
                System.out.println("NO");
                System.exit(0);
            }
        }
        System.out.println("YES");
    }
}