#include<iostream>

int eventsInRange(int* arr, int size, int start, int end) {
    end = std::min(end, size - 1);
    start = std::max(start, 0);
    if (start > end)
        return 0;
    return arr[end] - (start > 0 ? arr[start - 1] : 0);
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    int n;
    std::cin >> n;
    int k;
    std::cin >> k;
    int t;
    std::cin >> t;

    int officeMeetingsTillNow[n];
    int homeMeetingsTillNow[n];

    char c;
    std::cin >> c;

    officeMeetingsTillNow[0] = c == '1';
    homeMeetingsTillNow[0] = c == '2';

    for (int i = 1; i < n; i++) {
        char c;
        std::cin >> c;
        officeMeetingsTillNow[i] = officeMeetingsTillNow[i - 1] + (c == '1');
        homeMeetingsTillNow[i] = homeMeetingsTillNow[i - 1] + (c == '2');
    }

    int meetingsTotal = officeMeetingsTillNow[n - 1] + homeMeetingsTillNow[n - 1];

    if (officeMeetingsTillNow[n - 1] <= k) {
        int homeK = k - officeMeetingsTillNow[n - 1];
        int timeLeisure = n - std::max(homeMeetingsTillNow[n - 1] - homeK, 0);
        std::cout << timeLeisure << "\n";
        return 0;
    }

    int maxTimeLeisure = -1;

    for (int i = t; i < n; i++)
        for (int j = i; j < n - t; j++) {
            int meetingsDuringWork = eventsInRange(officeMeetingsTillNow, n, i, j) + eventsInRange(homeMeetingsTillNow, n, i, j);
            int meetingsDuringHome = eventsInRange(homeMeetingsTillNow, n, 0, i - t - 1) + eventsInRange(homeMeetingsTillNow, n, j + t + 1, n - 1);

            int neededMeetings = std::max(meetingsTotal - meetingsDuringWork - k, 0);

            int timeInHome = (i - t) + (n - (j + t + 1));

            if (meetingsDuringHome >= neededMeetings)
                maxTimeLeisure = std::max(maxTimeLeisure, timeInHome - neededMeetings);

        }
        
    
    std::cout << maxTimeLeisure << "\n";

    return 0;
    
}