#include<bits/stdc++.h> 

using namespace std;
int n,m,k;
string s;
vector<int>sum(100010);
bool check(int mid){
	vector<vector<int>>dp(k+10,vector<int>(100010,0x3f3f3f3f));
	vector<int>M(k+10,0x3f3f3f3f);
	M[0]=0;
	dp[0][0]=0;
	for(int i=mid;i<s.size();i++){
		//if(s[i]!='0')
		for(int j=1;j<=k;j++){
			if(s[i]=='0') dp[j][i]=M[j-1]+sum[i]-sum[i-mid];
			M[j-1]=min(M[j-1],dp[j-1][i-mid]);
		//	cout<<i<<" "<<j<<" "<<dp[j][i]<<" \n"[j==k-1];
		} 
	}
	for(int i=0;i<s.size();i++){
		if(dp[k][i]<=m)
			return 1;
	}
	
	return 0;
}
int main() {
    cin>>n>>m>>k;
    cin>>s;
    //s='0'+s;
    s+='0';
    
    for(int i=0;i<s.size();i++){
    	//if(i!=1) sum[i]+=;
    	sum[i+1]=-(s[i]-'1')+sum[i];
	}
    int l=0,r=1e5+10;
    while(l<r){
    	int mid=l+(r-l)/2;
    	if(check(mid)){
    		l=mid+1;
		}else{
			r=mid;
		}
		//cout<<l<<" "<<r<<endl;
	}
	if(l-1<=0)cout<<-1<<endl;
	else cout<<l-1<<endl;
    return 0;
}