#include <bits/stdc++.h>
#define long long long int
#define DEBUG
using namespace std;

// @author: pashka

int main() {
    ios::sync_with_stdio(false);

    int n, t, k;
    cin >> n >> t >> k;
    string s;
    cin >> s;
    vector<int> a = {1};
    for (int i = 0; i < n; i++) {
        if (s[i] == '0') {
            a.push_back(1);
        } else {
            a.back()++;
        }
    }

    n = a.size();
    int l = 0;
    int r = n + 2;
    const int INF = 1e9;
    while (r > l + 1) {
        int m = (l + r) / 2;
        vector<vector<int>> d(n + 1, vector<int>(k + 1, INF));
        d[0][0] = 0;
        int s = 0;
        int ii = 0;
        for (int i = 0; i < n; i++) {
            while (ii < n && s < m) {
                s += a[ii++];
            }
            for (int j = 0; j <= k; j++) {
                if (d[i][j] == INF) continue;
                d[i + 1][j] = min(d[i + 1][j], d[i][j]);
                if (j < k && s >= m) {
                    d[ii][j + 1] = min(d[ii][j + 1], d[i][j] + (ii - i - 1));
                }
            }
            s -= a[i];
        }
        if (d[n][k] > t) {
            r = m;
        } else {
            l = m;
        }
    }
    if (l == 1) l--;
    cout << l - 1 << "\n";

    return 0;
}