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);
        // n is between 2 and 10
        int n = in.nextInt();

        int startPointX =0, startPointY=0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            // Set StartPoint
            if(a0 == 0){
                startPointX = x;
                startPointY = y;
            }
            
            if((x != startPointX) && (y != startPointY)) {
                System.out.println("NO");
                return;
            }
                
            
        }
        System.out.println("YES");
        return;
    }
}