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#include <algorithm>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <deque>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define JOIN_(X, Y) X##Y
#define JOIN(X, Y) JOIN_(X, Y)
#define TMP JOIN(tmp, __LINE__)
#define PB push_back
#define SZ(x) int((x).size())
#define REP(i, n) for (int i = 0, TMP = (n); i < TMP; ++i)
#define FOR(i, a, b) for (int i = (a), TMP = (b); i <= TMP; ++i)
#define FORD(i, a, b) for (int i = (a), TMP = (b); i >= TMP; --i)

#ifdef DEBUG
#define DEB(x) (cerr << x)
#else
#define DEB(x)
#endif

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef unsigned int uint;

const int INF = 1e9 + 9;

struct Partial {
    int lost = 0, tentative = 0, free = 0;
};

ostream &operator<<(ostream &os, const Partial &p) {
    os << "Partial(Lost: " << p.lost << ", Tentative: " << p.tentative << ", Free: " << p.free
       << ")";
    return os;
}

string s;
vi prefix_sum_office = {0};
vi prefix_sum_remote = {0};
vi prefix_sum_free = {0};

void compute_prefix_sums(int n) {
    REP(i, n) {
        if (s[i] == '1') {
            prefix_sum_office.PB(prefix_sum_office.back() + 1);
            prefix_sum_remote.PB(prefix_sum_remote.back());
            prefix_sum_free.PB(prefix_sum_free.back());
        } else if (s[i] == '2') {
            prefix_sum_office.PB(prefix_sum_office.back());
            prefix_sum_remote.PB(prefix_sum_remote.back() + 1);
            prefix_sum_free.PB(prefix_sum_free.back());
        } else if (s[i] == '3') {
            prefix_sum_office.PB(prefix_sum_office.back());
            prefix_sum_remote.PB(prefix_sum_remote.back());
            prefix_sum_free.PB(prefix_sum_free.back() + 1);
        } else {
            throw "Unsupported char";
        }
    }
}

Partial analyze_home(int start, int end) {
    Partial partial;
    partial.lost = prefix_sum_office[end] - prefix_sum_office[start];
    partial.tentative = prefix_sum_remote[end] - prefix_sum_remote[start];
    partial.free = (prefix_sum_office[end] - prefix_sum_office[start]) +
                   (prefix_sum_free[end] - prefix_sum_free[start]);
    return partial;
}

Partial analyze_office(int start, int end, int t) {
    Partial partial;
    partial.lost = (prefix_sum_office[start + t] - prefix_sum_office[start]) +
                   (prefix_sum_remote[start + t] - prefix_sum_remote[start]) +
                   (prefix_sum_office[end] - prefix_sum_office[end - t]) +
                   (prefix_sum_remote[end] - prefix_sum_remote[end - t]);
    return partial;
}

int solve(int n, int k, int t, int start, int end) {
    int result = -1;
    Partial left = analyze_home(0, start);
    Partial right = analyze_home(end, n);
    Partial office = analyze_office(start, end, t);
    int sum_lost = left.lost + right.lost + office.lost;
    if (sum_lost > k) {
        return result;
    }
    int lost_left = k - sum_lost;
    int sum_free = left.free + right.free + office.free;
    int extra = min(lost_left, left.tentative + right.tentative);
    return sum_free + extra;
}

void inline one() {
    int n, k, t;
    cin >> n >> k >> t;
    cin >> s;
    compute_prefix_sums(n);
    int result = -1;
    Partial home_only = analyze_home(0, n);
    if (home_only.lost <= k) {
        int lost_left = k - home_only.lost;
        result = max(result, home_only.free + min(lost_left, home_only.tentative));
    }
    DEB("home_only=" << home_only << "\n");
    REP(start, n) {
        FOR(end, start + 2 * t, n) {
            int temp_result = solve(n, k, t, start, end);
            DEB("start=" << start << " end=" << end << " temp_result=" << temp_result << "\n");
            result = max(result, temp_result);
        }
    }
    cout << result << "\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    // int z; cin >> z; while(z--)
    one();
}