#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n, k; cin>>n>>k;
    string s; cin>>s;

    int buy=0, win=0;

    auto done=[&]() {
        for(auto& c: s) {
            win==0 ?  buy++ : win--;
            win+=c-'0';
            k--;
            if (k==0) return true;
        }
        return false;
    };

    while (k>0) {
        if (done()) break;
        if (win==0) {
            buy+=k/n*buy;
            k%=n;
        }

        int pwin=win, pbuy=buy;
        if (done()) break;
        if (pwin==win) {
            buy+=k/n*(buy-pbuy);
            k%=n;
        }
    }
    printf("%d\n", buy);
}