#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define pb push_back
#define x first
#define y second 
#define endl '\n'
const LL maxn = 4e05+7;
const LL N = 2e05+10;
const LL mod = 1e09+7;
const int inf = 0x3f3f3f3f;
const LL llinf = 5e18;
typedef pair<int,int>pl;
priority_queue<LL , vector<LL>, greater<LL> >mi;//小根堆
priority_queue<LL> ma;//大根堆
LL gcd(LL a, LL b){
	return b > 0 ? gcd(b , a % b) : a;
}

LL lcm(LL a , LL b){
	return a / gcd(a , b) * b;
}
int n , m , k;
LL sum[N];
LL pre[N];
string s;
LL dp[N][6][2];
bool check(int len){
	memset(dp , 0x3f3f3f , sizeof dp);
	dp[0][0][0] = 0;
	for(int i = 1 ; i <= n ; i ++){
		int num = s[i] - '0';
		int st = i;
		if(num == 0){
			dp[i][0][0] = 0;
			for(int j = 1 ; j <= k ; j ++){
				dp[i][j][0] = min(dp[i - 1][j][1] , dp[i - 1][j][0]);
				st -= len;
				if(st < 0)
					continue;
				st = pre[st];
				dp[i][j][1] = dp[st][0][0] + (sum[i] - sum[st] - j + 1);
				st--;
			}
		}
		else{
			dp[i][0][1] = 0;
			for(int j = 1 ; j <= k ; j ++){
				dp[i][j][1] = min(dp[i - 1][j][1] , dp[i - 1][j][0]);
				st -= len;
				if(st < 0)
					continue;
				st = pre[st];
				dp[i][j][1] = min(dp[i][j][1] , dp[st][0][0] + (sum[i] - sum[st] - j + 1));
				st--;
			}
		}
	}	
	int ans = min(dp[n][k][0] , dp[n][k][1]);
	if(ans > m){
		return false;
	}
	else{
		return true;
	}
}
void solve() 
{
	memset(dp , 0x3f3f3f , sizeof dp);
	cin >> n >> m >> k;
	cin >> s;
	s = " " + s;
	for(int i = 1 ; i <= n ; i ++){
		if(s[i] - '0' == 0){
			pre[i] = i;
			sum[i] = sum[i - 1] + 1;
		}
		else{
			pre[i] = pre[i - 1];
			sum[i] = sum[i - 1];
		}
	}
/*	dp[0][0][0] = 0;
	int len = 3;
	for(int i = 1 ; i <= n ; i ++){
		int num = s[i] - '0';
		int st = i;
		if(num == 0){
			dp[i][0][0] = 0;
			for(int j = 1 ; j <= k ; j ++){
				dp[i][j][0] = min(dp[i - 1][j][1] , dp[i - 1][j][0]);
				st -= len;
				if(st < 0)
					continue;
				st = pre[st];
				dp[i][j][1] = dp[st][0][0] + (sum[i] - sum[st] - j + 1);
				st--;
			}
		}
		else{
			dp[i][0][1] = 0;
			for(int j = 1 ; j <= k ; j ++){
				st -= len;
				if(st < 0)
					continue;
				st = pre[st];
				if(i == 8){
					cout << st << endl;
				}
				dp[i][j][1] = dp[st][0][0] + (sum[i] - sum[st] - j + 1);
				st--;
			}
		}
	}	
	cout << dp[8][2][1];*/
	int l = 0 , r = n / k;
	while(l < r){
		int mid = (l + r) / 2 + 1;
		if(check(mid)){
			l = mid;
		}
		else{
			r = mid - 1;
		}
	}
	cout << (l == 0 ? -1 : l);
}            
int main() 
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cout.precision(10);
    int t=1;
//	cin>>t;
    while(t--)
    {
    	solve();
    }
    return 0;
}