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#include <array>
#include <iostream>
#include <vector>

int main() {
    std::ios_base::sync_with_stdio(false);
    int n, k, t;
    std::cin >> n >> k >> t;
    char a;
    std::vector<int> mainVec;
    mainVec.assign(n, 0);
    std::array<std::vector<int>, 4> pref, suf;
    pref.fill(mainVec);
    suf.fill(mainVec);
    int x;
    std::cin >> a;
    x = a - '0';
    mainVec[0] = x;
    pref[x][0]++;
    for (int i = 1; i < n; i++) {
        std::cin >> a;
        pref[1][i] = pref[1][i - 1];
        pref[2][i] = pref[2][i - 1];
        pref[3][i] = pref[3][i - 1];
        x = a - '0';
        mainVec[i] = x;
        pref[x][i]++;
    }
    suf[mainVec[n - 1]][n - 1]++;
    for (int i = n - 2; i >= 0; i--) {
        suf[1][i] = suf[1][i + 1];
        suf[2][i] = suf[2][i + 1];
        suf[3][i] = suf[3][i + 1];
        suf[mainVec[i]][i]++;
    }
    constexpr bool debug = false;
    if constexpr (debug) {
        for (auto i : pref[1]) {
            std::cout << i;
        }
        std::cout << "\n";
        for (auto i : pref[2]) {
            std::cout << i;
        }
        std::cout << "\n";
        for (auto i : pref[3]) {
            std::cout << i;
        }
        std::cout << "\n";
        for (auto i : suf[1]) {
            std::cout << i;
        }
        std::cout << "\n";
        for (auto i : suf[2]) {
            std::cout << i;
        }
        std::cout << "\n";
        for (auto i : suf[3]) {
            std::cout << i;
        }
        std::cout << "\n";
    }
    if (k >= suf[1][0]) {
        x = suf[1][0] + suf[2][0];
        x = std::min(x, k);
        std::cout << suf[3][0] + x << "\n";
        exit(0);
    }
    int maxResult = -1;
    for (int i = t; i < n - t; i++) {
        for (int j = i; j < n - t; j++) {
            // std::cout << "\n" << i << " " << j << "---";
            int wrong = suf[2][i - t] - suf[2][i];
            // std::cout << wrong << " ";
            wrong += pref[2][j + t] - pref[2][j];
            // std::cout << wrong << " ";
            if (i > 0) {
                wrong += pref[1][i - 1];
            }
            // std::cout << wrong << " ";
            if (j < n - 1) {
                wrong += suf[1][j + 1];
            }
            // std::cout << wrong << " ";
            if (wrong <= k) {
                int result = 0;
                if (i - t > 0) {
                    result += pref[3][i - t - 1];
                    result += pref[1][i - t - 1];
                }
                if (j + t < n - 1) {
                    result += suf[3][j + t + 1];
                    result += suf[1][j + t + 1];
                }
                result += k - wrong;
                result = std::min(result, i - t + (n - 1 - (j + t)));
                maxResult = std::max(maxResult, result);
            }
        }
    }
    std::cout << maxResult << "\n";
    exit(0);
}