C++ :

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

string s;
int n, k;

int check(int l) {
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == '1') {
            i += l - 1;
            cnt++;
        }
    }
    return cnt <= k;
}

int main() {
//	freopen("test1.in","r",stdin);
    cin >> n >> k >> s;
    int f = 1;
    for (int i = 0; i < s.size(); i++) {
    	if (s[i] == '1') {
    		f = 0;
    		break;
		}
	}
	if (f) {
		cout << 0 << "\n";
		return 0; 
	}
    int l = 1, r = n, ans = 1;
    while (l <= r) {
        int mid = (l + r) / 2;
        if (check(mid))
            r = mid - 1, ans = mid;
        else
            l = mid + 1;
    }
    cout << ans;
    return 0;
}