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

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N, K;
    cin >> N >> K;

    string s;
    cin >> s;

    ll atari_per_box = 0;
    for(char c : s){
        if(c=='1'){
            atari_per_box += 1;
        }else if(c=='2'){
            atari_per_box += 2;
        }
    }

    // まず1周
    ll atari = 0;
    ll buy = 0;
    for(char c : s){
        if(atari==0){
            buy++;
        }else{
            atari--;
        }

        K--;
        if(K==0){
            p(buy);
            return 0;
        }

        if(c=='1'){
            atari += 1;
        }
        else if(c=='2'){
            atari += 2;
        }
    }

    if(K>100){
        ll middle = K - 100;

        // 中間
        ll loop = middle / N;
        if(atari_per_box >= N){
            //
        }else{
            buy += loop * (N-atari_per_box);
        }

        K -= N*loop;
    }

    // 最後
    while(true){
        for(char c : s){
            if(atari==0){
                buy++;
            }else{
                atari--;
            }

            K--;
            if(K==0){
                p(buy);
                return 0;
            }

            if(c=='1'){
                atari += 1;
            }
            else if(c=='2'){
                atari += 2;
            }
        }
    }
    
    return 0;
}