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