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#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n, k, t;
    string s;
    cin >> n >> k >> t;
    cin >> s;
    vector<int> prefix1(n + 1, 0);
    vector<int> prefix2(n + 1, 0);
    vector<int> prefix3(n + 1, 0);
    for (int y = 0; y < n; y++) {
        prefix1[y + 1] = prefix1[y] + (s[y] == '1');
        prefix2[y + 1] = prefix2[y] + (s[y] == '2');
        prefix3[y + 1] = prefix3[y] + (s[y] == '3');
    }
    int maxi = -1;
    int total1 = prefix1[n];
    if (total1 <= k) {
        int pozk = k - total1;
        int total2 = prefix2[n];
        int maxipom2 = min(total2, pozk);
        int czas = total1 + prefix3[n] + maxipom2;
        if (czas > maxi) {
            maxi = czas;
        }
    }
    if (2 * t <= n) {
        for (int start = 0; start <= n - 2 * t; start++) {
            int start_transit_end = start + t;
            for (int opusz = start_transit_end; opusz <= n - t; opusz++) {
                int biurostart = start + t;
                int biurokon = opusz;
                int biuro1 = prefix1[biurokon] - prefix1[biurostart];
                int opuszczone = prefix1[n] - biuro1;
                int przejdo = prefix2[start_transit_end] - prefix2[start];
                int przejz = prefix2[opusz + t] - prefix2[opusz];
                int przej = przejdo + przejz;
                int bazopusz = opuszczone + przej;
                if (bazopusz > k) continue;
                int dom2 = (prefix2[start] - prefix2[0]) + (prefix2[n] - prefix2[opusz + t]);
                int dom3 = (prefix3[start] - prefix3[0]) + (prefix3[n] - prefix3[opusz + t]);
                int pozk = k - bazopusz;
                int maxpom = min(dom2, pozk);
                int zad = dom3 + maxpom;
                if (zad > maxi) {
                    maxi = zad;
                }
            }
        }
    }

    cout << maxi;

    return 0;
}