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#include <bits/stdc++.h>
using namespace std;

int n, k, t;
string s;

int pref[4][8007];

void init(){
	s = '$'+s;
	for(int i=1; i<=n; i++){
		pref[1][i] = pref[1][i-1];
		pref[2][i] = pref[2][i-1];
		pref[3][i] = pref[3][i-1];
		if(s[i] == '1') pref[1][i]++;
		if(s[i] == '2') pref[2][i]++; 
		if(s[i] == '3') pref[3][i]++; 
	}
}

int query(int a, int b, int r){
	if(b < a) return 0;
	return pref[r][b] - pref[r][a-1];
}

int cnt(int sa, int sb, int ka, int kb){
	int tam = query(sa,sb,1) + query(sa,sb,2);
	int powrot  = query(ka,kb,1) + query(ka,kb,2);
	int tmp = query(1,sa-1,1) + query(kb+1,n,1); //ile jest spotkan w biurze gdy on jest w domu
	if(tam + powrot + tmp > k) return -1;
	return query(1,sa-1,3) + query(kb+1,n,3) + tmp + 
		min(query(1,sa-1,2) + query(kb+1,n,2), k - tam - powrot - tmp);
}

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	
	cin >> n >> k >> t >> s;
	
	init();
	
	int ans = -1;
	
	for(int i=1; i<=n; i++){ //wyrusza w i, dojezdza w i+t-1
		for(int j=i+t; j+t-1<=n; j++){ //wraca w j, dojezdza w j+t
			ans = max(ans, cnt(i,i+t-1, j, j+t-1));
		}
	}
	
	//caly dzien w domu
	int tmp = 0;
	if(query(1,n,1) <= k){
		tmp = query(1,n,3) + query(1,n,1) + min(query(1,n,2), k - query(1,n,1));
		ans = max(ans, tmp);
	}
	
	cout << ans << '\n';
}