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();
        Set ux = new HashSet();
        Set uy = new HashSet();
        
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();

            ux.add(x);
            uy.add(y);
            
            if(ux.size() > 1 && uy.size() > 1) {
                System.out.println("NO");
                System.exit(0);
            }
        }
        System.out.println("YES");
    }
}