#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
const int N = 200010;
typedef long long ll;
typedef pair<int, int> pii;
std::mt19937 rng {std::chrono::steady_clock::now().time_since_epoch().count()};

template <typename T>
void debug(T x) {
    cerr << x << '\n';
}

template <typename T, typename... Args>
void debug(T x, Args... args) {
    cerr << x << ' ';
    debug(args...);
}

void solve() {
    int n, m, k;
    cin >> n >> m >> k;
    string s;
    cin >> s;
    s = ' ' + s;
    vector<int> pre(n + 1), to(n + 1);
    for (int i = 1; i <= n; i ++ ) {
        pre[i] = pre[i - 1] + (s[i] == '0');
        to[i] = (s[i] == '1'? to[i - 1] : i);
    }
    auto check = [&](int mid) {
        vector<vector<int>> dp(n + 1, vector<int> (6, 0x3f3f3f3f));
        dp[0][0] = 0;
        for (int i = 1; i <= n; i ++ ) {
            if (i >= mid) {
                for (int j = 1; j <= k; j ++ ) {
                    dp[i][j] = min(dp[i - 1][j], dp[max(0, to[i - mid] - 1)][j - 1] + pre[i] - pre[i - mid]);
                }
            }
        }
        return dp[n][k] <= m;
    };
    int l = 0, r = n;
    while (l < r) {
        int mid = l + r + 1 >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (! r) {
        cout << -1 << '\n';
    } else {
        cout << r << '\n';
    }
}

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