A. New Year Transportation

 

http://codeforces.com/contest/500/problem/A

 

 1 import java.util.Scanner;
 2 
 3 public class Main {
 4     static final int MAX = Integer.MAX_VALUE;
 5 
 6     public static void main(String[] args) {
 7         Scanner io = new Scanner(System.in);
 8         int n = io.nextInt(), t = io.nextInt();
 9         int[] a = new int[n + 1];
10         for (int i = 1; i <= n-1; i++) a[i] = io.nextInt();
11         int x=1;
12         while (x<t){
13             x+=a[x];
14             if (x==t) { System.out.println("YES");return; }
15         }
16         System.out.println("NO");
17     }
18 
19 
20 }