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();
        if(n < 2){
            System.out.println("NO");
            return;
        }
        int x1 = in.nextInt();
        int y1 = in.nextInt();
        boolean isHorizontal = true;
        boolean isVertical = true;
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(isHorizontal){
                if(x == x1) isHorizontal &= true;
                else isHorizontal &= false;
            }
            if(isVertical){
                if(y == y1) isVertical &= true;
                else isVertical &= false;
            }
            if(!isHorizontal && !isVertical){
                System.out.println("NO");
                return;
            }
        }
        System.out.println("YES");
    }
}