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 flag=0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(x!=0&&y!=0){
                flag=1;
                break;
            }}
            if(flag==0)
                System.out.println("YES");
            else
                 System.out.println("NO");
        }
        
    }