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

int dp[200003][8][2];

int main() {
	cin.tie(0) -> sync_with_stdio(0);
	int n, m, k;
	string s;
	cin >> n >> m >> k >> s;
	vector<int> cnt_0(n + 1);
	s.insert(0, " ");
	for (int i = 1; i <= n; ++i)
		cnt_0[i] = cnt_0[i - 1] + (s[i] == '0');
	int l = 0, r = 2e5;
	auto check = [&](int tar) {
		for (int i = 0; i <= n; ++i)
			for (int j = 0; j <= k; ++j) dp[i][j][0] = dp[i][j][1] = 0x3f3f3f3f;
		dp[0][0][0] = 0;
		for (int i = 1; i <= n; ++i) {
			for (int j = 0; j <= k; ++j) {
				if (s[i] == '1') {
					dp[i][j][0] = min({dp[i][j][0], dp[i - 1][j][0], dp[i - 1][j][1]});
					dp[i][j][1] = min({dp[i][j][1], dp[i - 1][j][0], dp[i - 1][j][1]});
				}
				else {
					dp[i][j][0] = min({dp[i][j][0], dp[i - 1][j][0], dp[i - 1][j][1]});
					dp[i][j][1] = min(dp[i][j][1], min(dp[i - 1][j][0], dp[i - 1][j][1]) + 1);
				}
				if (j >= 1 && i >= tar && dp[i - tar][j - 1][0] != 0x3f3f3f3f)
						dp[i][j][1] = min(dp[i][j][1], dp[i - tar][j - 1][0] + cnt_0[i] - cnt_0[i - tar]);
			}
		}
		// for (int i = 1; i <= n; ++i) {
		// 	for (int j = 0; j <= k; ++j) {
		// 		cerr << "i = " << i << " j = " << j << '\n';
		// 		cerr << dp[i][j][0] << ' ' << dp[i][j][1] << "\n";
		// 	}
		// 	cerr << '\n';
		// }
		// for (int i = 1; i <= n; ++i) {
  //           for (int j = 0; j <= k; ++j) {
  //               cerr << i << ' ' << j << ' ' << 0 << ' ' << dp[i][j][0] << '\n';
  //               cerr << i << ' ' << j << ' ' << 1 << ' ' << dp[i][j][1] << '\n';
  //           }
  //       }
		return min(dp[n][k][0], dp[n][k][1]) <= m;
	};
	// check(3);
	while (l < r) {
		int mid = (l + r + 1) >> 1;
		// cerr << l << ' ' << r << ' ' << mid << '\n';
		if (check(mid)) l = mid;
		else r = mid - 1;
	}
	if (!l) cout << "-1\n";
	else cout << l << '\n';
	return 0;
}