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#include <algorithm>
#include <cstdio>

constexpr auto MAX_SIZE = 8002;
constexpr auto OFFICE = 0;
constexpr auto REMOTE = 1;
constexpr auto FREE = 2;

struct Data {
  Data() : sum(0) {
    for (int i = 0; i < MAX_SIZE; ++i) {
      prefix[i] = 0;
      suffix[i] = 0;
    }
  }
  int sum;
  int prefix[MAX_SIZE];
  int suffix[MAX_SIZE];
};

int sum(const Data* data, const int start, const int stop, const unsigned char v) {
  if (start <= stop) {
    return data[v].sum - data[v].prefix[start - 1] - data[v].suffix[stop + 1];
  } else {
    return 0;
  }
}

int result(const Data* data, const int n, const int neededMeetings, const int t, const int start, const int stop) {
  const auto startFixed = start + t;
  const auto stopFixed = stop - t;
  const auto officeMeetings = sum(data, startFixed, stopFixed, OFFICE) + sum(data, startFixed, stopFixed, REMOTE);
  const auto remoteMeetings = sum(data, 1, start - 1, REMOTE) + sum(data, stop + 1, n, REMOTE);
  const auto noMeetings = start - 1 + n - stop;
  if (neededMeetings <= officeMeetings) {
    return noMeetings;
  } else if (neededMeetings <= officeMeetings + remoteMeetings) {
    return noMeetings - (neededMeetings - officeMeetings);
  } else {
    return -1;
  }
}

int main() {
  int n, k, t;
  Data data[3];
  unsigned char type[8000], v;

  scanf("%d %d %d\n", &n, &k, &t);
  for (int i = 1; i <= n; ++i) {
    scanf("%c\n", &v);
    v -= '1';
    type[i] = v;
    data[v].sum++;
    data[OFFICE].prefix[i] = data[OFFICE].prefix[i - 1];
    data[REMOTE].prefix[i] = data[REMOTE].prefix[i - 1];
    data[FREE].prefix[i] = data[FREE].prefix[i - 1];
    data[v].prefix[i]++;
  }
  for (int i = n; i >= 1; --i) {
    v = type[i];
    data[OFFICE].suffix[i] = data[OFFICE].suffix[i + 1];
    data[REMOTE].suffix[i] = data[REMOTE].suffix[i + 1];
    data[FREE].suffix[i] = data[FREE].suffix[i + 1];
    data[v].suffix[i]++;
  }

  if (data[OFFICE].sum <= k) {  // go to office not needed
    const auto mettings = data[REMOTE].sum + data[OFFICE].sum;
    printf("%d\n", n - std::max(0, mettings - k));
  } else {
    const auto neededMeetings = data[REMOTE].sum + data[OFFICE].sum - k;
    int r = -1;
    for (int i = 1; i <= n - 2 * t + 1; ++i) {
      for (int j = i + 2 * t - 1; j <= n; ++j) {
        r = std::max(r, result(data, n, neededMeetings, t, i, j));
      }
    }
    printf("%d\n", r);
  }
  return 0;
}