#include <fstream>
#include <iomanip>
using namespace std;
ifstream fin("secv3.in");
ofstream fout("secv3.out");
int N,U,L,i,j,p=1;
double v[30005],t[30005],mx,x;
int main()
{fin>>N>>U>>L;
 for(i=1;i<=N;i++)
    {fin>>x;v[i]=v[i-1]+x;}
 for(i=1;i<=N;i++)
    {fin>>x;t[i]=t[i-1]+x;}
 for(i=1;i<=N;i++)
    {if(j<i-L)j++;
     if(i>=U){if((v[i]-v[i-U])/(t[i]-t[i-U])>(v[i]-v[j])/(t[i]-t[j]))j=i-U;
     mx=max(mx,(v[i]-v[j])/(t[i]-t[j]));//fout<<mx<<" "<<i<<" "<<j<<"\n";
             }
    }
 fout<<fixed<<setprecision(2)<<mx;
}