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();
         int a[] = new int[n];
            int b[] = new int[n];
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            a[a0]=x;
            b[a0]=y;
        }
        int count=0;
        for(int i=0;i<(n-1);i++){
            if(a[i]==a[i+1]){
                count++;
            }
            else break;
        }
        if(count==n-1)
            System.out.println("YES");
        else System.out.println("NO");
    }
}