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#include <array>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

int solve(int n, int k, int t, const string& s)
{
    array<int, 3> cnt{};

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

    if (cnt[0] <= k)
        return min(cnt[0] + cnt[1], k) + cnt[2];

    int res = -1;

    array<int, 3> left{};

    for (int i = 0; i < t; ++i)
    {
        ++left[s[i] - '1'];
    }

    int l = 0;

    while (true)
    {
        if (left[0] + left[1] <= k)
        {
            array<int, 3> inside{};
            array<int, 3> right{};

            ++inside[s[l + t] - '1'];

            int r = l + t + 1;

            for (int i = 0; i < t; ++i)
            {
                ++right[s[r + i] - '1'];
            }

            while (true)
            {
                array<int, 3> outside{};

                for (int i = 0; i < 3; ++i)
                {
                    outside[i] = cnt[i] - left[i] - inside[i] - right[i];
                }

                if (left[0] + left[1] + right[0] + right[1] + outside[0] <= k)
                    res = max(res, min(outside[0] + outside[1], k - left[0] - left[1] - right[0] - right[1]) + outside[2]);

                if (r + t == n)
                    break;

                ++inside[s[r] - '1'];
                --right[s[r] - '1'];
                ++right[s[r + t] - '1'];
                ++r;
            }
        }

        if (l + 2 * t + 1 == n)
            break;

        --left[s[l] - '1'];
        ++left[s[l + t] - '1'];
        ++l;
    }

    return res;
}

int main()
{
    int n, k, t;
    string s;
    cin >> n >> k >> t >> s;

    int res = solve(n, k, t, s);

    cout << res << endl;

    return 0;
}