import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
    static boolean allXeq(int n,int a[])
        {
        boolean f=true;
        for(int x=0;x<n-1;x++)
            {
            if(a[x]!=a[x+1]){f=false;break;}
        }
        return f;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int x[] = new int[5];
        int y[] = new int [5];
        String ans="YES";
        for(int a0 = 0; a0 < n; a0++){
            x[a0] = in.nextInt();
            y[a0] = in.nextInt();
            
        }
        if(allXeq(n,x) || allXeq(n,y))System.out.println("YES");
        else System.out.println("NO");
    }
}