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) {
        int firstX = 0;
        int firstY = 0;
        boolean xBroke = false;
        boolean yBroke = false;
        
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if (a0 == 0){
                firstX = x;
                firstY = y;               
            }
            
            if ( firstX != x) {
                xBroke = true;
            }
            if ( firstY != y) {
                yBroke = true;
            }
            
            if (xBroke && yBroke) {
                System.out.println("NO");
                break;
            }
        }
        
        if ( (xBroke && !yBroke) || (!xBroke && yBroke) ){
            System.out.println("YES");
        }
    }
}