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#include <bits/stdc++.h>
using namespace std;

using vi = vector<int>;
#define all(x) x.begin(), x.end()

#define OFFICE '1'
#define REMOTE '2'
#define FREE_TIME '3'

int main()
{
    int n, k, t;
    cin >> n >> k >> t;
    string s;
    cin >> s;
    int n_off = count(all(s), OFFICE);
    int n_rem = count(all(s), REMOTE);
    int must = max(n_off + n_rem - k, 0);

    if (n_rem >= must)
    {
        cout << n - must << '\n';
        return 0;
    }

    vi lowest(n - t + 1, -1);
    int current = n_rem - count(s.begin(), s.begin() + t, REMOTE);
    for (int i = 0; i < current; i++)
    {
        lowest[i] = 0;
    }
    for (int i = 1; i < n - t + 1; i++)
    {
        if (s[i - 1] != FREE_TIME)
            current++;
        if (s[i + t - 1] == REMOTE)
            current--;
        if (lowest[current] == -1)
        {
            lowest[current] = i;
        }
    }

    vi n_cum_meets(n + 1, 0);
    for (int i = 0; i < n; i++)
    {
        n_cum_meets[i + 1] = n_cum_meets[i] + (s[i] != FREE_TIME);
    }

    int meets_unavailable = (t - 1) - count(s.begin(), s.begin() + t - 1, FREE_TIME);
    int max_slack = -1;
    for (int i = 0; i < n - t + 1; i++)
    {
        if (s[i + t - 1] != FREE_TIME)
            meets_unavailable++;

        int min_meets = meets_unavailable + must;
        int j = min_meets >= lowest.size() ? -1 : lowest[min_meets];
        if (j != -1)
        {
            int n_meets_in_office = n_cum_meets[j] - n_cum_meets[i + t];
            int time_in_office = (j + t - i);
            int meets_outside_office = max(must - n_meets_in_office, 0);
            int slack = n - time_in_office - meets_outside_office;

            max_slack = max(max_slack, slack);
        }

        if (s[i] == REMOTE)
            meets_unavailable--;
    }
    cout << max_slack << '\n';

    return 0;
}