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

public class Solution {
    static int x, y;
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        boolean flag = true;
        for(int a0 = 0; a0 < n; a0++){
            x = in.nextInt();
            y = in.nextInt();
            while((x > 0 && y > 0) || (y > 0 && x > 0)) {
                flag = false;
                break;
            }      
        }
        if(flag){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
        
    }
}