#include <bits/stdc++.h>
using namespace std;
#define st first
#define nd second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define BOOST ios_base::sync_with_stdio(0), cin.tie(0)
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;

const int N = 8e3 + 5;
int pref[N][4];

int main(){
	BOOST;
	int n, k, t;
	cin >> n >> k >> t;
	string s; cin >> s;
	s = '#' + s;
	for(int i=1; i<=n; i++){
		for(int j=1; j<=3; j++){
			pref[i][j] = pref[i-1][j];
		}
		pref[i][s[i] - '0']++;
	}

	auto seg = [](int i, int a, int b){ // prawy wyłącznie
		return pref[b-1][i] - pref[a-1][i];
	};

	auto go = [&](int be, int en){
		int res = seg(3, 1, be) + seg(3, en+t, n+1);
		res += seg(1, 1, be) + seg(1, en+t, n+1);
		
		int skip = seg(1, 1, be+t) + seg(1, en, n+1);
		skip += seg(2, be, be+t) + seg(2, en, en+t);
		if(skip > k) return -1;
		
		int f2 = seg(2, 1, be) + seg(2, en+t, n+1);
		res += min(f2, k - skip);
		return res;
	};

	int mx = -1;
	int res = seg(3, 1, n+1) + seg(1, 1, n+1);
	int skip = seg(1, 1, n+1);
	if(skip <= k){
		int f2 = seg(2, 1, n+1);
		res += min(f2, k - skip);
		mx = res;
	}
	for(int i=1; i<=n; i++){
		for(int j=i+t; j+t<=n+1; j++){
			mx = max(mx, go(i, j));
		}
	}
	cout << mx << "\n";
}