#include <iostream>
#include <queue>
#include <vector>

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
    
    int n, k;
    std::cin >> n >> k;
    std::vector<char> s(n);
    std::queue<int> iceQueue;
    for(int i=0; i<n; ++i){
        std::cin >> s[i];
    }
    auto FillQueue = [&]{
        static auto it = s.begin();
        while(static_cast<int>(iceQueue.size()) <= n){
            iceQueue.push((*it)-'0');
            ++it;
            if(it==s.end()) it=s.begin();
        }
    };
    int buyNum = 0;
    int freeNum = 0;
    for(int i=0; i<k; ++i){
        FillQueue();
        if(freeNum == 0){
            ++buyNum;
        }else{
            --freeNum;
        }
        freeNum += iceQueue.front();
        iceQueue.pop();
    }
    std::cout << buyNum << "\n";

    return 0;
}