#include <bits/stdc++.h>
#define int long long

using namespace std;

constexpr int inf = 1E18;

void solve () {
    int n, m, k;
    cin >> n >> m >> k;

    string s;
    cin >> s;

    s = "0" + s;

    vector <int> pre (n + 2);
    for (int i = 1; i <= n; i ++) {
        pre[i] = pre[i - 1] + (s[i] == '0');
    }

    auto check = [&](int x) {
        vector <array <int, 3>> p;
        for (int l = 1, r = 1; l <= n; l ++) {
            if (s[l - 1] != '0') {
                continue;
            }
            while (r < n && (r - l + 1 < x || s[r + 1] == '1')) {
                r ++;
            }
            if (r - l + 1 >= x) {
                p.push_back ({l, r, pre[r] - pre[l - 1]});
            }
        }
        vector dp (n + 1, vector <int> (k + 1, inf));
        vector predp (n + 1, vector <int> (k + 1, inf));
        for (int i = 0; i <= 0; i ++) {
            dp[0][i] = predp[0][i] = 0;
        }
        int i = 1;
        for (auto [l, r, cost] : p) {
            while (i <= r) {
                predp[i] = predp[i - 1];
                i ++;
            }
            for (int j = 1; j <= k; j ++) {
                dp[r][j] = min (dp[r][j], predp[max (0LL, l - 2)][j - 1] + cost);
                predp[r][j] = min (predp[r][j], dp[r][j]);
            }
        }
        int minn = inf;
        for (int i = 1; i <= n; i ++) {
            minn = min (minn, dp[i][k]);
        }
        return minn <= m;
    };

    int l = 1, r = n;
    while (l < r) {
        int mid = (l + r + 1) / 2;
        if (check (mid)) {
            l = mid;
        } else {
            r = mid - 1;
        }
    }

    if (! check (l)) {
        cout << -1 << '\n';
    } else {
        cout << l << '\n';
    }
}

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

    int T = 1;
    // cin >> T;

    while (T --) {
        solve ();
    }
}