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();
        Integer prevX = null, prevY = null;
        boolean xChanged = false, yChanged = false;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(prevX != null && x != prevX) 
                xChanged = true;
            if(prevY != null && y != prevY) 
                yChanged = true;
            if(xChanged && yChanged) 
                break;
            prevX = x;
            prevY = y;
        }
        if(!xChanged || !yChanged)
            System.out.println("YES");
        else
            System.out.println("NO");
    }
}