#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...);
}
// dp[i][j][1/0] -> 从前i个中选，满足 >=mid 有几个，且最后一段满不满足条件
// dp[i][j][1] <- dp[i - mid][j - 1][0] + count(i - mid + 1, i);
// dp[i][j][0] <- min(dp[i - 1][j][0], dp[i - 1][j][1]);
// ans -> dp[n][mid][0] / dp[n][mid][1] >= k;
int n, m, k;
int dp[N][6][2], a[N];
string s;

bool check(int mid) {
    for (int i = 0; i <= n; i ++ ) {
        for (int j = 0; j <= 5; j ++ ) {
            dp[i][j][0] = dp[i][j][1] = 1e9;
        }
    }
    dp[0][0][0] = 0;
    // for (int i = 1; i <= n; i ++ ) {
    //     if (i >= mid) {
    //         for (int j = 1; j <= k; j ++ ) {
    //             dp[i][j][1] = dp[i - mid][j - 1][0] + mid - (a[i] - a[i - mid]);
    //         }
    //     }
    //     for (int j = 1; j <= k; j ++ ) {
    //         if (s[i] == '0') {
    //             dp[i][j][0] = min(dp[i - 1][j][0], dp[i - 1][j][1]);
    //         }
    //     }
    // }
    for (int j = 1; j <= k; j ++ ) {
        for (int i = 1; i <= n; i ++ ) {
            if (i >= mid) {
                dp[i][j][1] = dp[i - mid][j - 1][0] + mid - (a[i] - a[i - mid]);
            }
            dp[i][j][0] = min(dp[i - 1][j][0], dp[i - 1][j][1]);
        }
    }
    int ans = 1e9;
    for (int i = 0; i <= n; i ++ ) {
        ans = min(ans, min(dp[i][k][0], dp[i][k][1]));
    }
    return (ans <= m);
}

void solve() {
    cin >> n >> m >> k >> s;
    s = ' ' + s;
    for (int i = 1; i <= n; i ++ ) {
        a[i] = a[i - 1] + (s[i] == '1' ? 1 : 0);
    }
    int l = 0, r = 2e6;
    while (l < r) {
        int mid = l + r + 1 >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (r > 1) {
        cout << r << '\n';
    } else {
        if (r == 1) {
            if (check(r)) {
                cout << r << '\n';
            } else {
                cout << -1 << '\n';
            }
        } else {
            cout << -1 << '\n';
        }
    }
}

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