#include<bits/stdc++.h>
using namespace std;
int n, m, k, f[200010][6][2], ans = 0, sum[200010];
string s;
bool check(int x)
{
	//cout<<x<<endl;
	for(int i = 0;i <= n;i ++)for(int j = 0;j <= k;j ++)
	{
		f[i][j][0] = 998244353;
		f[i][j][1] = 998244353;
		//if(j == 0)f[i][j][0] = 0;
	}
	f[0][0][0] = 0;
	for(int i = 1;i <= n;i ++)
	{
		for(int j = 0;j <= k;j ++)
		{
			if(j != 0 and i >= x)f[i][j][1] = f[i - x][j - 1][0] + x - (sum[i] - sum[max(i - x, 0)]);
			if(s[i] == '0')f[i][j][0] = min(f[i - 1][j][0], f[i - 1][j][1]);
			if(s[i] == '1')
			{
				f[i][j][1] = min(f[i][j][1], f[i - 1][j][1]);
				f[i][j][0] = f[i - 1][j][0];
			}
		}
	}
	//cout<<f[n][k][0]<<' '<<f[n][k][1]<<'\n';
	return min(f[n][k][0], f[n][k][1]) <= m;
}
signed main() {
	cin>>n>>m>>k;
	cin>>s;
	//cout<<s<<endl;
	for(int i = 1;i <= n;i ++)
	{
		sum[i] = sum[i - 1] + (s[i - 1] == '1');
	}
//	for(int i = 1;i <= n;i ++)cout<<sum[i]<<' ';
//	cout<<endl;
	int l = 0, r = n;
	while(l <= r)
	{
		int mid = l + r >> 1;
		if(check(mid))
		{
			l=mid + 1;
			ans=mid;
		}
		else r = mid - 1;
	}
	if(ans == 0)cout<<-1<<endl;
	else cout<<ans;
	return 0;
}