#include<bits/stdc++.h>
using namespace std;
const int MAX=2e5+5;
int n,m,k,tot;
int f[MAX][6][2],pre[MAX],sum[MAX];
string s;
struct Area{
	int l,r,len;
};
bool check(int x){
	memset(f,0x3f,sizeof(f));
	f[0][0][0]=1;
	for(int i=1;i<=n;++i){
		if(s[i]=='0'){
			f[i][0][0]=0;
			f[i][0][1]=1;
		}
		f[i][0][1]=0;	
		for(int j=1;j<=k;++j){
			if(s[i]=='0'){
				f[i][j][0]=min(f[i-1][j][0],f[i-1][j][1]);
			}
			for(int l=0;i-l>=x;++l){
				f[i][j][1]=min(f[i][j][1],f[l][j-1][0]-sum[i]+sum[l]+x);
			}
		//	if(x==3)
		//	cout<<i<<" "<<j<<" "<<f[i][j][0]<<" "<<f[i][j][1]<<endl;
		}
	}
	return min(f[n][k][0],f[n][k][1])<=m;
}
int main(){
	cin>>n>>m>>k;
	cin>>s;
	s=" "+s;
	int l=0,r=n,res=-1;
	for(int i=1;i<=n;++i){
		if(s[i]=='1')
			sum[i]=sum[i-1]+1;
		else
			sum[i]=sum[i-1];
	}
	while(l<=r){
		int mid=l+r>>1;
	//	cout<<mid<<endl;
		if(check(mid)){
			res=mid;
			l=mid+1;
		}
		else{
			r=mid-1;
		}
	}
	
	cout<<res; 
}