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];
        int c=0,d=0;
        for(int a0 = 0; a0 < n; a0++){
            a[a0] = in.nextInt();
            b[a0] = in.nextInt();
            }
        for(int i=0;i<n;i++)
            {
            if(a[i]==0)
                {
                c++;
            }
             
            
        }
        if(c==n)
            {
            System.out.println("YES");
        }
        else
            System.out.println("NO");
    }
}