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