#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <vector>

#define rep(i, x, y) for (int i = x; i <= y; i++)
using namespace std;
const int N = 2e5 + 5;
int n, m, k;
string s;
int dp[N][6][2];

int main() {
    ios::sync_with_stdio(false);
	cin.tie(0);
    cin >> n >> m >> k;
    cin >> s;
    vector<int> pre(n + 1);
    rep(i, 1, n) pre[i] = pre[i - 1] + (s[i - 1] == '0');


    auto check = [&](int x) {
        if (x == 0) return true;
        rep(i, 0, n) rep(j, 0, k) dp[i][j][0] = dp[i][j][1] = 1e9;
        dp[0][0][0] = 0;
        rep(i, 1, n) rep(j, 0, k) {
            if (i >= x && j >= 1) dp[i][j][1] = dp[i - x][j - 1][0] + pre[i] - pre[i - x];
            dp[i][j][0] = min(dp[i - 1][j][0], dp[i - 1][j][1]);
        }
        return min(dp[n][k][0], dp[n][k][1]) <= m;
    };

    int l = 0, r = 2e5;
    while (l < r) {
        int mid = (l + r + 1) >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (l) cout << l;
    else cout << "-1";
    return 0;
}