#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <ctime>
#include <cstdlib>
 
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define FFOR(i,a,b) for(int i=(a);i<=(b);i++)
#define REP(i,b) FOR(i,0,b)
#define RREP(i,b) FFOR(i,1,b)
#define PB push_back
#define F first
#define S second
#define BE(c) c.begin(),c.end()
using namespace std;
typedef long long LL;
typedef LL ut;
typedef long double ld;
typedef pair<ut,ut> pr;
typedef vector<pr> Vpr;
typedef vector<ut> VI;
typedef pair<ut,pr> ppr;
typedef priority_queue<pr,Vpr, greater<pr> > PQ;
const int SIZE=1e+5 + 1;
const ut INF=1<<29;
const ld eps=1e-6;
const LL mod=1e+6 + 3;


int main() {
	int n, k;
	string s;
	cin >> n >> k >> s;
	int now = 0, f = 0, cnt = 0;
	int ans = 0;
	bool end = false;
	do{
		ans++;
		int c = s[now] - '0';
		do {
			if(f > 0){
				c = s[now] - '0';
				f--;
			}
			if(c == 1){
				f++;
			}
			else if(c == 2){
				f += 2;
			}
			now++;
			cnt++;
			if(ans == 1 && now >= n && f != 0){
				end = true;
				now = 0;
				break;
			}
			if(k <= cnt){
				now = 0;
				break;
			}
			now %= n;
		}while(f != 0);
	}while(now != 0);
	if(end){
		cout << ans << endl;
		return 0;
	}
	ans = ans * (k / cnt);
	int p = k % cnt;
	if(!p){
		cout << ans << endl;
		return 0;
	}
	cnt = 0;
	end = false;
	do{
		ans++;
		char c = s[now];
		do {
			if(f > 0){
				c = s[now];
				f--;
			}
			if(c == '1'){
				f++;
			}
			else if(c == '2'){
				f += 2;
			}
			now++;
			cnt++;
			if(p <= cnt){
				end = true;
				break;
			}
			now %= n;
		}while(f != 0);
	}while(!end);
	cout << ans << endl;
 	return 0;
}