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#include <bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define reunique(v) v.resize(std::unique(v.begin(), v.end()) - v.begin())
#define sz(v) ((int)(v).size())

#define vec1d(x) vector<x>
#define vec2d(x) vector<vec1d(x)>
#define vec3d(x) vector<vec2d(x)>
#define vec4d(x) vector<vec3d(x)>

#define ivec1d(x, n, v) vec1d(x)(n, v)
#define ivec2d(x, n, m, v) vec2d(x)(n, ivec1d(x, m, v))
#define ivec3d(x, n, m, k, v) vec3d(x)(n, ivec2d(x, m, k, v))
#define ivec4d(x, n, m, k, l, v) vec4d(x)(n, ivec3d(x, m, k, l, v))

#define nl "\n"

#ifdef LOCAL
#include "pretty_print.hpp"
#define dbg(...) debug_out(__LINE__, #__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(...) 42
#endif

typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;

template <typename T> T sqr(T x) { return x * x; }
template <typename T> T abs(T x) { return x < 0? -x : x; }
template <typename T> T gcd(T a, T b) { return b? gcd(b, a % b) : a; }
template <typename T> bool chmin(T &x, const T& y) { if (x > y) { x = y; return true; } return false; }
template <typename T, typename T2> bool chmax(T &x, const T2& y) { if (x < y) { x = y; return true; } return false; }

auto random_address = [] { char *p = new char; return (uint64_t) p; };
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count() * (random_address() | 1));
mt19937_64 rngll(chrono::steady_clock::now().time_since_epoch().count() * (random_address() | 1));

const int MAXN = 8042;

short f[MAXN][MAXN][3];
int a[MAXN];


int main(int /* argc */, const char** /* argv */)
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n, k, t;
    string s;
    while (cin >> n >> k >> t >> s) {
        memset(f, 0x80, sizeof(f));
        f[0][0][0] = 0;

        a[0] = 0;
        for (int i = 1; i <= n; ++i) {
            a[i] = a[i - 1] + (s[i - 1] != '3');
        }

        for (int i = 0; i < n; ++i) {
            for (int j = k; j >= 0; --j) {
                auto t0 = f[i][j][0];
                auto t1 = f[i][j][1];
                auto t2 = f[i][j][2];

                chmax(f[i + 1][j][1], t1);

                if (s[i] == '1') {
                    chmax(f[i + 1][j + 1][0], t0 + 1);
                    chmax(f[i + 1][j + 1][2], t2 + 1);
                } else if (s[i] == '2') {
                    chmax(f[i + 1][j + 1][0], t0 + 1);
                    chmax(f[i + 1][j + 1][2], t2 + 1);
                    chmax(f[i + 1][j][0], t0);
                    chmax(f[i + 1][j][2], t2);
                } else {
                    chmax(f[i + 1][j][0], t0 + 1);
                    chmax(f[i + 1][j][2], t2 + 1);
                }
            }

            if (i + 1 >= t) {
                int p = i + 1 - t;
                auto x = a[i + 1] - a[p];
                for (int j = x; j <= k; ++j) {
                    chmax(f[i + 1][j][1], f[p][j - x][0]);
                    chmax(f[i + 1][j][2], f[p][j - x][1]);
                }
            }
        }

        auto ans = -1;
        for (int i = 0; i <= k; ++i) {
            chmax(ans, f[n][i][0]);
            chmax(ans, f[n][i][2]);
        }
        cout << ans << nl;
    }

#ifdef LOCAL
    cerr << "Time execute: " << clock() / (double)CLOCKS_PER_SEC << " sec" << endl;
#endif
    return 0;
}