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#include <vector>
#include <map>
#include <string>
#include <cstdio>
#include <iostream>
#include <ostream>
#include <algorithm>
#include <cmath>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned char ubyte;

constexpr ld EPS = 1e-9;
constexpr ld PI = 3.141592653589793238462643383279502884L;
constexpr int INF = (int)1e9 + 5;
constexpr ll LINF = (ll)1e18 + 5;

bool eq(ld a, ld b) {
  return fabs(a - b) < EPS;
}

template<class T>
T sqr(const T & x) { return x * x; }

template<class T>
ll abs(const T & x) { return x < 0 ? -x : x; }

template<class T>
ll myround(const T & x) { return x < 0 ? x - 0.5 : x + 0.5; }

template<class T>
bool chmin(T & x, const T & y) {
  if (y < x) {
    x = y;
    return true;
  }
  return false;
}

template<class T>
ostream & operator <<(ostream & os, const vector<T> & v) {
  os << "{";
  for (typename vector<T>::const_iterator it = v.begin(); it != v.end(); ++it) {
    os << *it;
    if ((it + 1) != v.end()) os << ", ";
  }
  os << "}";
  return os;
}

template<class P, class Q>
ostream & operator <<(ostream & os, const pair<P, Q> & p) {
  return os << "(" << p.first << ", " << p.second << ")";
}

template<class T>
bool chmax(T & x, const T & y) {
  if (x < y) {
    x = y;
    return true;
  }
  return false;
}

template<class IntegerType = int>
IntegerType nextInt() {
  IntegerType x = 0;
  bool p = false;
  char c;
  do {
    c = getchar();
  } while (c <= 32);
  if (c == '-') {
    p = true;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return (p ? -x : x);
}

string nextToken() {
  static const size_t MAX_LEN = 500500;
  static char str[MAX_LEN];
  scanf("%s", str);
  return str;
}

//template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
//template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;

#define all(a) (a).begin(), (a).end()

void no_solution()
{
  puts("-1");
  exit(0);
}

vector<int> calc(string s, char c)
{
  int n = (int)s.size();
  vector<int> a(n + 1);
  a[0] = 0;
  for ( int i = 0; i < n; i++ )
  {
    a[i + 1] = a[i];
    if ( s[i] == c )
      a[i + 1] += 1;
  }
  return a;
}

void testcase()
{
  int n = nextInt<int>();
  int k = nextInt<int>();
  int t = nextInt<int>();
  string s = nextToken();
  vector<int> a1 = calc(s, '1');
  vector<int> a2 = calc(s, '2');
  vector<int> a3 = calc(s, '3');
  auto segment = [&](int l, int r, int& a, int& b, int& c)
  {
    b = a2[r + 1] - a2[l];
    a = a1[r + 1] - a1[l];
    c = a3[r + 1] - a3[l];
  };
  auto best_ans = [&](int& res, int newres)
  {
    if ( res == -1 )
      res = newres;
    else if ( newres > res )
      res = newres;
  };
  int spotkanie_w_biurze;
  int zdalne_spotkanie;
  int brak_obowiazkow;
  segment(0, n - 1, spotkanie_w_biurze, zdalne_spotkanie, brak_obowiazkow);
  int spotkania = zdalne_spotkanie + spotkanie_w_biurze;
  //std::cout << spotkania << std::endl;
  int res = -1;
  if ( spotkanie_w_biurze <= k )
  {
    int cur = brak_obowiazkow + spotkanie_w_biurze;
    int skip_spotkanie = std::min(k - spotkanie_w_biurze, zdalne_spotkanie);
    cur += skip_spotkanie;
    best_ans(res, cur);
  }
  for (int i = 0; i + t <= n; i++)
  {
    for ( int j = i + t; j + t <= n; j++ )
    {
      int spotkanie_w_biurze1;
      int zdalne_spotkanie1;
      int brak_obowiazkow1;
      int spotkanie_w_biurze2;
      int zdalne_spotkanie2;
      int brak_obowiazkow2;
      int spotkanie_w_biurze3;
      int zdalne_spotkanie3;
      int brak_obowiazkow3;
      segment(0, i - 1, spotkanie_w_biurze1, zdalne_spotkanie1, brak_obowiazkow1);
      segment(i + t, j - 1, spotkanie_w_biurze2, zdalne_spotkanie2, brak_obowiazkow2);
      segment(j + t, n - 1, spotkanie_w_biurze3, zdalne_spotkanie3, brak_obowiazkow3);
      spotkanie_w_biurze1 += spotkanie_w_biurze3;
      zdalne_spotkanie1 += zdalne_spotkanie3;
      brak_obowiazkow1 += brak_obowiazkow3;
      int tot_attending = zdalne_spotkanie1 + spotkanie_w_biurze2 + zdalne_spotkanie2;
      //std::cout << i << " " << j << " " << tot_attending << std::endl;
      if ( tot_attending < spotkania - k )
        continue;
      int cur = spotkanie_w_biurze1 + brak_obowiazkow1;
      int toadd = std::min(tot_attending - (spotkania - k), zdalne_spotkanie1);
      cur += toadd;
      best_ans(res, cur);
    }
  }
  printf("%d\n", res);
}

int main() {
#ifdef LOCAL
  freopen("input.txt", "r", stdin);
#endif

  int t = 1;
  while (t--)
    testcase();
}