#include <iostream>
#include <sstream>
#include <math.h>
#include <vector>
#include <array>
#include <algorithm>
#include <queue>
#include <numeric>
#include <map>
#include <set>
#include <bitset>

using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define SUM(a) accumulate(ALL(a), 0)
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

typedef pair<int, int> pos;
int pos::*x = &pos::first;
int pos::*y = &pos::second;

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/
int N, K;
string s;

signed main()
{
    vector<int> ices;
    cin >> N >> K >> s;
    REP(i,N) ices.push_back(atoi(s.substr(i,1).c_str()));
    
    int perN = 0; // 一箱(N本)食べるのに必要な購入数
    int bonus = 0; // 一箱食べた後に残ってるボーナス
    REP(i,N) {
        int ice = ices[i];
        if (bonus) bonus--;
        else perN++;
        bonus += ice;
    }
    
    int box = K / N; // 食べきる箱の数
    int mod = K % N; // 食べ切らない箱で買う本数
    
    int cnt = 0;
    if (box) {
        cnt = perN + max((box - 1) * (perN - bonus), 0LL);
    } else {
        bonus = 0;
    }
    REP(i,mod) {
        int ice = ices[i];
        if (bonus) bonus--;
        else cnt++;
        bonus += ice;
    }
    
    cout << cnt << endl;
    
    return 0;
}