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

#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
typedef vector<int>vint;
typedef pair<int,int>pint;

int N,K;
int S[100000];

int main(){
    cin>>N>>K;
    string str;cin>>str;
    rep(i,N)S[i]=str[i]-'0';
    rep(i,10*N)S[i+N]=S[i];

    int len=0,val=0,get=0;
    rep(i,100000){
        if(i%N==0&&i&&get==0){
            len=i;
            break;
        }
        if(K==i){
            cout<<val<<endl;
            return 0;
        }
        if(get){
            get--;
        }
        else{
            val++;
        }
        get+=S[i];
        if(get>1145){
            cout<<val<<endl;
            return 0;
        }
    }

    int ans=(K/len)*val;
    K%=len;
    get=0;
    rep(i,K){
        if(get){
            get--;
        }
        else{
            ans++;
        }
        get+=S[i];
    }

    cout<<ans<<endl;
    return 0;
}