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

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef double db;


const int N = 8007;
int dp[N][N][3];

int pref[3][N];

void upd(int& a, int b)
{
	a = max(a, b);
}

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	
	int n, k, T;
	cin >> n >> k >> T;
	
	string s;
	cin >> s;
	FOR(i, 0, n)
	{
		pref[1][i + 1] = pref[1][i] + (s[i] == '1');
		pref[2][i + 1] = pref[2][i] + (s[i] == '2');
	}
	
	
	FOR(i, 0, n + 1)
		FOR(j, 0, k + 1)
			fill(dp[i][j], dp[i][j] + 3, -1);
	dp[0][0][0] = 0;
	FOR(i, 0, n)
	{
		FOR(j, 0, k + 1)
		{
			FOR(t, 0, 3)
			{
				if(dp[i][j][t] == -1)
					continue;
					
				upd(dp[i + 1][j + 1][t], dp[i][j][t] + 1);
				if(s[i] == '3')
				{
					upd(dp[i + 1][j][t], dp[i][j][t] + (t != 1));
				}
				else if(s[i] == '2' || (s[i] == '1' && t == 1))
				{
					upd(dp[i + 1][j][t], dp[i][j][t]);				
				}
				if(i + T <= n && t != 2)
				{
					int skipped = (pref[2][i + T] - pref[2][i]) + (pref[1][i + T] - pref[1][i]);
					if(j + skipped <= k)
					{
						upd(dp[i + T][j + skipped][t + 1], dp[i][j][t]);
	
					}
				}
			}
		}	
	}
	
	int ans = -1;
	FOR(j, 0, k + 1)
	{
		upd(ans, dp[n][j][0]);
		upd(ans, dp[n][j][2]);
	}
	cout << ans << "\n";

	
	//cout << 1.0 * clock() / CLOCKS_PER_SEC << "\n";
	
	
	
	
	return 0;
}