package no078;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		char[] s = sc.next().toCharArray();
		Pair[] bef = new Pair[n];
		int bought = 0;
		int eaten = 0;
		int index = 0;
		boolean naive = false;
		while(true) {
			if (!naive && bef[index] != null) {
				int d = eaten - bef[index].eaten;
				int units = (k-eaten) / d;
				eaten += units * d;
				bought += units * (bought - bef[index].bought);
				naive = true;
				if (eaten >= k) {
					break;
				}
			}
			if (!naive) {
				bef[index] = new Pair(bought,eaten);
			}
			bought++;
			int atari = 1;
			for(int i=0;i<=n;i++) {
				atari--;
				eaten++;
				atari += s[index] - '0';
				index = (index + 1) % n;
				if (atari == 0) {
					break;
				}
				if (i == n) {
					eaten = k;
				}
			}
			if (eaten >= k) {
				break;
			}
		}
		System.out.println(bought);
	}

	static class Pair {
		int bought,eaten;
		public Pair(int bought,int eaten) {
			this.bought = bought;
			this.eaten = eaten;
		}
	}

}