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#include <bits/stdc++.h>

using namespace std;

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, k, t;
    cin >> n >> k >> t;
    string s;
    cin >> s;
    vector<int> offline(n + 1, 0), online(n + 1, 0), all(n + 1, 0);
    for(int i = 0; i < n; i++) {
        offline[i + 1] = (s[i] == '1') + offline[i];
        online[i + 1] = (s[i] == '2') + online[i];
        all[i + 1] = (s[i] <= '2') + all[i];
    }

    int used = offline[n];
    int on = online[n];
    if(used <= k) {
        cout << n - on + min(on, k - used) << '\n';
        return 0;
    }

    int best = -1;
    for(int i = t; i <= n - t; i++) {
        for(int j = i + 1; j <= n - t + 1; j++) {
            used = offline[i - t] + all[i] - all[i - t] + all[j + t - 1] - all[j - 1] + offline[n] - offline[j + t - 1];
            if(used > k) continue;

            int on = online[i - t] + online[n] - online[j + t - 1];
            best = max(best, i - t + n - (j + t - 1) - on + min(on, k - used));
        }
    }

    cout << best << '\n';
}