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"); } }