#include<unordered_map>
#include<functional>
#include<algorithm>
#include<iostream>
#include<cassert>
#include<cstring>
#include<cstdlib>
#include<numeric>
#include<iomanip>
#include<bitset>
#include<random>
#include<cstdio>
#include<string>
#include<vector>
#include<array>
#include<ctime>
#include<stack>
#include<queue>
#include<cmath>
#include<set>
#include<map>

#define fi first
#define se second
#define pii pair<int,int>
#define NO cout << "NO\n"
#define YES cout << "YES\n"
#define stop system("pause");
#define debug printf("++ ++\n");
#define cout(a) cout << (#a) << " = " << a << endl;
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 2e5;
const int K = 5;
random_device gen;
mt19937 rnd(gen());
int n, m, k;
int sum[N + 5], dp[N + 5][K + 5];
//dp[i][j]表示处理到第 i 位时, 前面已经存在 j 个 >m 的 '1' 串
char s[N + 5];

/* 终点是一切概率的结束，也是一切期望的开始 */
/* *
 * 可能做法: 基础算法(思维, 暴力, 贪心, 二分dp)
 * */

bool check(int mid) {
	for (int i = 0; i <= n; i++) for (int j = 0; j <= k; j++) dp[i][j] = INF;
	dp[0][0] = 0;
	for (int i = mid; i <= n; i++) {
		int l = i - mid + 1, r = i;
		for (int j = k; j >= 0; j--) {
			dp[i][j] = dp[i - 1][j];
			if (s[r + 1] == '0' && j >= 1) dp[i][j] = min(dp[i][j], dp[max(0, l - 2)][j - 1] + (sum[r] - sum[l - 1]));
		}
	}
	return dp[n][k] <= m;
}

void solve() {
	cin >> n >> m >> k >> (s + 1);
	s[0] = '0';
	s[n + 1] = '0';
	for (int i = 1; i <= n; i++) sum[i] = sum[i - 1] + (s[i] == '0');
	int l = 1, r = n, ans = -1;
	while (l <= r) {
		int mid = l + r >> 1;
		if (check(mid)) ans = mid, l = mid + 1;
		else r = mid - 1;
	}
	cout << ans << '\n';
}

signed main() {
	std::ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
	int t = 1;
//	cin >> t;
	while (t--) solve();
	return 0;
}