import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static boolean checkPoint(int x, int y, int x0, int y0, int a) {
        if(a == Integer.MIN_VALUE) {
            return x == x0;
        } else if( a == Integer.MAX_VALUE) {
            return y == y0;
        }
        return false;
    }
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int x0 = in.nextInt();
        int y0 = in.nextInt();
        int x1 = in.nextInt();
        int y1 = in.nextInt();
        int a; 
        if(x1 - x0 == 0) {
            a = Integer.MIN_VALUE;    
        } else if(y1 - y0 == 0){
            a = Integer.MAX_VALUE;
        } else {
            System.out.println("NO");
            return;
        }
        
        String result = "YES";
        for(int a0 = 2; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(!checkPoint(x, y, x0, y0, a)) {
                result = "NO";
                break;
            }
        }
        
        System.out.println(result);
    }
}