#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cctype>
#include<math.h>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#include<set>
#include<map>
#include<stdlib.h>
#include<iomanip>

using namespace std;

#define ll long long
#define ld long double
#define EPS 0.0000000001
#define INF 1e9
#define LINF (ll)INF*INF
#define MOD 1000000007
#define rep(i,n) for(int i=0;i<(n);i++)
#define loop(i,a,n) for(int i=a;i<(n);i++)
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)

#define int ll //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int,int> pii;
typedef vector<pii> vp;

int gcd(int a, int b){
    if(b==0) return a;
    return gcd(b,a%b);
}
int lcm(int a, int b){
    return a*b/gcd(a,b);
}

int n,k;
string s;
vi a,used;

int f(int now, int t){
    if(a[now] != -1)return a[now];
    if(used[now]){
        a[now] = LINF;
        return LINF;
    }
    used[now]++;
    int ret = 1,ne;
    if(s[now] >= '1'){
        ret += f((now+ret)%n,t);
    }
    if(s[now] == '2' && ret < LINF){
        ret += f((now+ret)%n,t);
    }
    a[now] = ret;
    return ret;
}

signed main(void) {
    cin >> n >> k;
    cin >> s;
    a = vi(n,-1);
    rep(i,n)if(a[i] == -1){
        used = vi(n);
        a[i] = f(i,i);
    }
    //rep(i,n)cout << " " << a[i];cout << endl;
    int ans = 0;
    int ind = 0;
    int sum = 0;
    vp memo(n,pii(-1,-1));
    while(sum < k){
        if(memo[ind] != pii(-1,-1)){
            int left = k - sum;
            int d1 = sum - memo[ind].first;
            int d2 = ans - memo[ind].second;
            int t = left/d1 - 1;
            if(t > 0){
                sum += t*d1;
                ans += t*d2;
            }
        }
        memo[ind] = pii(sum,ans);
        sum += a[ind];
        ind = (ind + a[ind])%n;
        ans++;
    }
    cout << ans << endl;
}