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

const int max_n = 8e3+5;

int N, K, T;
int A[max_n];
int Pref[max_n][3];

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> N >> K >> T;
    for (int i = 1; i <= N; i++) {
        char c; cin >> c;
        A[i] = c - '1';
        if (i > 0) {
            Pref[i][0] = Pref[i-1][0];
            Pref[i][1] = Pref[i-1][1];
            Pref[i][2] = Pref[i-1][2];
        }
        Pref[i][A[i]]++;
        // cerr << i << " " << Pref[i][0] << " " << Pref[i][1] << " " << Pref[i][2] << "\n";
    }
    A[0] = 5;
    // A[N+1] = 5;
    // Pref[N+1][0] = Pref[N][0];
    // Pref[N+1][1] = Pref[N][1];
    // Pref[N+1][2] = Pref[N][2];

    N += 1;

    int Score = -1;

    int SpotkaniaOminiete = Pref[N-1][0];
    int ZadaniaGwarantowane = Pref[N-1][2] + SpotkaniaOminiete;
    int SpotkaniaLubZadania = Pref[N-1][1];
    // cerr << SpotkaniaOminiete << " " << ZadaniaGwarantowane << " " << SpotkaniaLubZadania << "\n";

    if (SpotkaniaOminiete <= K) {
        int Rem = K - SpotkaniaOminiete;
        ZadaniaGwarantowane += min(Rem, SpotkaniaLubZadania);
        Score = max(Score, ZadaniaGwarantowane);
    }

    for (int l = 0; l < N - 2 * T; l++) {
        for (int r = l + T + 1; r < N - T; r++) {
            /*
            Sekcja [0, l] i [r + T + 1, N-1] -> tylko spotkania zdalne lub zadanka
            [l + T + 1, r] -> tylko spotkania zdalne lub biurowe
            */

            int ZadaniaGwarantowane = Pref[N-1][2] - Pref[r+T][2] + Pref[l][2];
            ZadaniaGwarantowane += Pref[N-1][0] - Pref[r+T][0] + Pref[l][0];
            int SpotkaniaLubZadania = Pref[N-1][1] - Pref[r+T][1] + Pref[l][1];
            int SpotkaniaOminiete = Pref[N-1][0] - Pref[r][0] + Pref[l + T][0];
            SpotkaniaOminiete += Pref[r+T][1] - Pref[r][1] + Pref[l+T][1] - Pref[l][1];
            // cerr << l << " " << r << "\n";
            // cerr << ZadaniaGwarantowane << " " << SpotkaniaLubZadania << " " << SpotkaniaOminiete << "\n";

            if (SpotkaniaOminiete > K) continue;
            int Rem = K - SpotkaniaOminiete;
            ZadaniaGwarantowane += min(Rem, SpotkaniaLubZadania);
            Score = max(Score, ZadaniaGwarantowane);
            // cerr << ZadaniaGwarantowane << "\n";
        }
    }

    cout << Score << "\n";
    
}