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#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pii pair<int,int>
#define pl pair<ll,ll>
#define F first
#define S second
#define pq priority_queue
#define all(x) x.begin(), x.end()
#define deb(x) cout << #x << " = " << x << '\n';
#define deb2(x,y) cout << #x << " = " << x << ", " << #y << " = " << y << '\n';

constexpr int M = 1e9+7;
constexpr int N = 8e3+7;
constexpr bool debug = 0;

int pref[N][3];

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int n, kok, t; cin >> n >> kok >> t;
	string sus; cin >> sus;
	for(int i = 0; i < n; ++i){
		pref[i+1][0] = pref[i][0];
		pref[i+1][1] = pref[i][1];
		pref[i+1][2] = pref[i][2];
		if(sus[i] == '1') ++pref[i+1][0];
		if(sus[i] == '2') ++pref[i+1][1];
		if(sus[i] == '3') ++pref[i+1][2];
	}
	int best = -1;

	if(pref[n][0] <= kok){
		best = max(best, pref[n][0]+pref[n][2]+min(kok-pref[n][0], pref[n][1]));
	}

	for(int i = 1; i <= n; ++i){
		for(int j = i+t; j+t-1 <= n; ++j){
			int skipped = pref[i+t-1][0] + pref[n][0]-pref[j-1][0];
			skipped += pref[i+t-1][1]-pref[i-1][1] + pref[j+t-1][1]-pref[j-1][1];
			if(skipped <= kok){
				int remain = pref[i-1][2]+pref[n][2]-pref[j+t-1][2];
				remain += pref[i-1][0]+pref[n][0]-pref[j+t-1][0];
				int toad = pref[i-1][1]+pref[n][1]-pref[j+t-1][1];
				best = max(best, remain + min(kok-skipped, toad));

				//deb2(i, j);
				//deb(best);
			}
		}
	}
	cout << best << '\n';

	return 0;
}