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#include <bits/stdc++.h>
 
using namespace std;
 
#define endl '\n'
#define L long long
#define MP make_pair
#define REP(i, n) for(int i = 0; i < n; ++i)
#define REPR(i, n) for(int i = n - 1; i >= 0; --i)
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define FORR(i, a, b) for(int i = b - 1; i >= a; --i)
#define EB emplace_back
#define ST first
#define ND second
#define S size
#define RS resize
 
template<class T> using P = pair<T, T>;
template<class T> using V = vector<T>;
 
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, k, t;
    string s;
    cin >> n >> k >> t >> s;
    V<int> h(n + 2);
    REP(i, n) {
        h[i + 1] = int(s[i] - '0');
    }
    h[n + 1] = 3;

    V<int> pref(n + 2, 0);
    FOR(i, 1, n + 2) {
        pref[i] = pref[i - 1] + (h[i] != 3);
    }

    int inf = int(1e9);

    int dp[3][n + 2][k + 1];
    REP(p, 3) {
        REP(i, n + 2) {
            REP(j, k + 1) {
                dp[p][i][j] = -inf;
            }
        }
    }

    dp[0][0][0] = 0;

    FOR(i, 1, n + 2) {
        if (h[i] == 2) {
            dp[0][i][0] = dp[0][i - 1][0];
        } else if (h[i] == 3) {
            dp[0][i][0] = dp[0][i - 1][0] + 1;
        }

        FOR(j, 1, k + 1) {
            if (h[i] == 1) {
                dp[0][i][j] = dp[0][i - 1][j - 1] + 1;
            } else if (h[i] == 2) {
                dp[0][i][j] = max(dp[0][i - 1][j], dp[0][i - 1][j - 1] + 1);
            } else {
                dp[0][i][j] = dp[0][i - 1][j] + 1;
            }
        }

        REP(j, k + 1) {
            dp[1][i][j] = dp[1][i - 1][j];
            if (i > t && pref[i - 1] - pref[i - 1 - t] <= j) {
                int d = pref[i - 1] - pref[i - 1 - t];
                dp[1][i][j] = max(dp[1][i][j], dp[0][i - 1 - t][j - d]);
            }
        }

        REP(j, k + 1) {
            int r1 = -inf, r2 = -inf;
            if (i > t && pref[i - 1] - pref[i - 1 - t] <= j) {
                int d = pref[i - 1] - pref[i - 1 - t];
                r2 = dp[1][i - 1 - t][j - d];
            }
            if (i > t && pref[i - 1] - pref[i - 1 - t] <= j - 1) {
                int d = pref[i - 1] - pref[i - 1 - t];
                r1 = dp[1][i - 1 - t][j - d - 1];
            }

            int z = j == 0 ? -inf : dp[2][i - 1][j - 1];
            if (h[i] == 1) {
                dp[2][i][j] = max(r1, z) + 1;
            } else if (h[i] == 2) {
                int m1 = max(r1, z) + 1;
                int m2 = max(r2, dp[2][i - 1][j]);
                dp[2][i][j] = max(m1, m2);
            } else {
                dp[2][i][j] = max(r2, dp[2][i - 1][j]) + 1;
            }
        }
    }

    int res = 0;
    REP(j, k + 1) {
        res = max(res, dp[0][n + 1][j]);
        res = max(res, dp[2][n + 1][j]);
    }
    cout << res - 1 << '\n';
}

// g++ -std=c++20 -Wall -Wextra -Wshadow -Wconversion -D_GLIBCXX_DEBUG pra.cpp -o pra