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

#define int long long  

template <typename T>
struct Fenwick {
    int n;
    vector<T> a;
    Fenwick(int n_ = 0) {
        init(n_);
    }    
    void init(int n_) {
        n = n_;
        a.assign(n + 1, 1e18);
    }	    
    void add(int x, const T &v) {
        for (int i = x; i <= n; i += i & -i) {
            a[i] = min(a[i], v);
        }
    }
    T sum(int x) {
        T ans = 1e18;
        for (int i = x; i > 0; i -= i & -i) {
            ans = min(ans, a[i]);
        }
        return ans;
    }
    T rangeSum(int l, int r) {
        return sum(r) - sum(l - 1);
    }
};

Fenwick<int> f[6];

signed main() {  
    ios::sync_with_stdio(false);
    cin.tie(nullptr);  

	int n, m, k;
	cin >> n >> m >> k;

	string s;
	cin >> s;
	s = " " + s;

	vector<int> nxt(n + 1);
	int lst = n + 1;

	for (int i = n; i >= 1; i--) {
		nxt[i] = lst;
		if (s[i] == '0') {
			lst = i;
		}
	}

	// for (int i = 1; i <= n; i++) {
	// 	cerr << nxt[i] << " \n"[i == n];
	// }

	vector<int> cnt(n + 1);
	for (int i = 1; i <= n; i++) {
		cnt[i] = cnt[i - 1] + (s[i] == '0');
	}
	
	auto check = [&](int x) {
		vector dp(n + 1, vector<int>(k + 1, 1e18));
		for (int i = 0; i <= n; i++) {
			dp[i][0] = 0;
		}

		for (int i = 0; i <= k; i++) {
			f[i].init(n + 10);
		}
		vector<int> p(n + 1, 1e18);
		f[0].add(1, 0);
		for (int i = 1; i <= n; i++) {
			if (s[i - 1] == '1') {
				continue;
			}
			if (i + x - 1 > n) {
				continue;
			}
			p[i] = nxt[i + x - 1] + 1;
			for (int j = 1; j <= k; j++) {
				dp[i][j] = min(dp[i][j], f[j - 1].sum(i) + cnt[p[i] - 2] - cnt[i - 1]);
			}
			for (int j = 0; j <= k; j++) {
				f[j].add(p[i], dp[i][j]);
			}
		}

		for (int i = 1; i <= n; i++) {
			if (dp[i][k] <= m) {
				return true;
			}
		}
		return false;
	};

	int l = 0, r = n + 1;
	while (l + 1 != r) {
		int m = (l + r) / 2;
		if (check(m)) {
			l = m;
		} else {
			r = m;
		}
	}

	if (l == 0) {
		cout << -1 << "\n";
	} else {
		cout << l << "\n";
	}

    return 0;
}