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


int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int n, k, t;
    cin >> n >> k >> t;
    string s;
    cin >> s;
    s = '#' + s + '#';
    vector <array <int, 4>> pref(s.size(), {0, 0, 0}), suf(s.size(), {0, 0, 0});
    for (int i = 1; i < s.size(); i++) {
        pref[i] = pref[i - 1];
        if (s[i] == '1') pref[i][1]++;
        if (s[i] == '2') pref[i][2]++;
        if (s[i] == '3') pref[i][3]++;
    }

    for (int i = s.size() - 2; i >= 0; i--) {
        suf[i] = suf[i + 1];
        if (s[i] == '1') suf[i][1]++;
        if (s[i] == '2') suf[i][2]++;
        if (s[i] == '3') suf[i][3]++;
    }

    int ans = -1;
    if (pref[n][1] <= k) {
        int _k = k - pref[n][1];
        ans = pref[n][3] + pref[n][1] + min(_k, pref[n][2]);
    }

    for (int i = 0; i <= n; i++) {
        for (int j = n + 1; j >= 0; j--) {
            if (j - i - 1 >= 2 * t) {
                int _k = k - (pref[i + t][2] - pref[i][2]) - (pref[i + t][1] - pref[i][1]);
                _k = _k - (pref[j - 1][2] - pref[j - 1 - t][2]) - (pref[j - 1][1] - pref[j - 1 - t][1]);
                _k -= pref[i][1];
                _k -= suf[j][1];
                if (_k < 0) continue;
                ans = max(ans, pref[i][3] + suf[j][3] + pref[i][1] + suf[j][1] + min(_k, pref[i][2] + suf[j][2]));
            }
        }
    }
    cout << ans << '\n';
}