import java.util.*;

public class Exercise148{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int k = sc.nextInt();
    String s = sc.next();
    String sumS = s;
    if(k > n){
      for(int i = 1; i < (int)Math.ceil((double)k / (double)n); i++){
        sumS += s;
      }
    }
    long p = 0;
    long g = 0;
    char[] sArray = sumS.toCharArray();
    for(int i = 0; i < k; i++){
      if(g > 0){
        if(c(sArray[i]) > 0){
          g += c(sArray[i]);
        }
        g--;
      }else{
        if(c(sArray[i]) > 0){
          g += c(sArray[i]);
        }
        p++;
      }
    }
    System.out.println(p);
  }
  private static int c(char ch){
    return Character.getNumericValue(ch);
  }
}