using System;
using System.Linq;

public class MyClass
{
    public static void Main()
    {
        var array = Array.ConvertAll<string, int>(Console.ReadLine().Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries), int.Parse);
        int N = array[0];
        int K = array[1];
        var str = Console.ReadLine();
        var strNew = str;
        int cnt = 0;
        for (int i = 0; i < str.Length; i++)
        {
            cnt--;
            cnt = Math.Max(cnt, 0);
            cnt += str[i] - '0';
        }//for i
        for (int i = 0; i < strNew.Length; i++)
        {
            if (cnt > 0 && strNew[i] == '0' || strNew[i] == '2')
            {
                if (strNew[i] == '0')
                {
                    cnt--;
                }//if
                else
                {
                    cnt++;
                }//else
                strNew = strNew.Substring(0, i) + "1" + strNew.Substring(i + 1);
            }//if
        }//for i
        long res = Count(str, Math.Min(str.Length, K));
        res += (K - str.Length) / str.Length * strNew.Count(x => x == '0');
        res += Count(strNew, (K - str.Length > 0 ? K % str.Length : 0));
        Console.WriteLine(res);
    }

    private static int Count(string str, int need)
    {
        int res = 0;
        int cnt = 0;
        for (int i = 0; i < need; i++)
        {
            cnt--;
            if (cnt < 0)
            {
                res++;
                cnt++;
            }//if
            cnt += str[i] - '0';
        }//for i
        return res;
    }

}