#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))
#define REPEAT(i, k, n)     for(int(i)=(k);(i)<((k)+(n));++(i))


int dp[10000];

int main(){
    int N,K;
    cin >> N >> K;

    string s;
    cin >> s;
    dp[0] = 0;

    int get = 0, buy = 0;
    while(1){
        int cnt = 1, add = 1; buy++;
        while(add){
            int n = s[get%N]-'0';
            get++;
            add--; add += n;
            cnt += n;
            if(get > K) break;
        }
        dp[buy] = get;
        if(get > K) break;
        if(get % N == 0) break;
    }
    int res = 0;
    if(K >= get){
        res += (K / get) * buy;
        K %= get;
    }
    for(int i = 0; i <= buy; i++){
        if(dp[i] >= K){
            res += i;
            break;
        }
    }
    cout << res << endl;

    return 0;
}