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#include <memory.h>
#include <stdio.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <ranges>
#include <locale>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <string>
#include <string_view>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

// #pragma GCC target("sse,sse2,sse3,ssse3,sse4")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

using namespace std;

#define fst first
#define snd second
#define X first
#define Y second
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back

#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define sz(v) ((int)(v).size())
#define sqr(x) ((x) * (x))

typedef long long ll;
typedef double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;

// #define next ajksdslk
// #define prev aklsfjk

mt19937_64 mt_rand(chrono::system_clock::now().time_since_epoch().count());

template <typename T1, typename T2>
inline bool upmax(T1& a, T2 b) {
  return (a < b ? (a = b, true) : false);
}

template <typename T1, typename T2>
inline bool upmin(T1& a, T2 b) {
  return (b < a ? (a = b, true) : false);
}

const int maxn = (int)(1e6 + 10);
const int maxlog = 21;
const int base = (int)1e9 + 7;
const ld eps = (ld)1e-9;
const ld PI = acos(-1.);
// const int pp = 41;
const int inf = 1e9;
const ll llinf = 2e18;

const int MOD = 998244353;



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

  
  int skip = 0;
  int canJoin = 0;
  int days = 0;

  int ans = -1;

  auto addHome = [&](char c, int add) {
    if (c == '1') {
      skip += add;
    } else if (c == '2') {
      canJoin += add;
    }
    days += add;
  };

  auto addWork = [&](char c, int add) {
    // if (c == '1') {
    //   canJoin += add;
    // } else if (c == '2') {
    //   canJoin += add;
    // }
  };

  auto addDrive = [&](char c, int add) {
    if (c == '1') {
      skip += add;
    } else if (c == '2') {
      skip += add;
    }
  };

  vector<int> fl(n, 0);
  auto calc = [&]() {
    if (skip > k) return -1;
    int canSkip = k - skip;
    int haveToJoin = max(0, canJoin - canSkip);
    return days - haveToJoin;
  };


  auto apply = [&](int i, int add) {
    if (fl[i] == 0) {
      addHome(s[i], add);
    } else if (fl[i] == 1) {
      addWork(s[i], add);
    } else {
      addDrive(s[i], add);
    }
  };

  auto changeState = [&](int i, int st) {
    apply(i, -1);
    fl[i] = st;
    apply(i, 1);
  };

  for (int i = 0; i < n; i ++) {
    addHome(s[i], 1);
  }
  upmax(ans, calc());


  for (int i = 0; i < 2 * t; i ++) {
    changeState(i, 2);
  }
  for (int i = t; i + t < n; i++) {
    if (i - t - 1 >= 0) {
      changeState(i - t - 1, 0);
    }
    if (i - 1 >= 0) {
      changeState(i - 1, 2);
    }
    for (int j = i; j + t + 1 < n; j ++) {
      changeState(j, 2);
    }
    for (int j = i + t + 1; j < n; j ++) {
      changeState(j, 0);
    }
    
    for (int j = i; j + t < n; j ++) {
      changeState(j, 1);
      changeState(j + t, 2);
  
      upmax(ans, calc());
    }

  }
  cout << ans << "\n";
  
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

#ifdef LOCAL
  freopen("input.txt", "r", stdin);
#endif
  
  int t = 1;
  // cin >> t;
  for (int i = 1; i <= t; i++) {
    // cout << "Case #" << i << ": ";
    solve();
  }
  
  return 0;
  
  
  
}