#include <fstream>

using namespace std;
ifstream f("secv3.in");
ofstream g("secv3.out");
int sumaa[30001],sumab[30001],i,ma,x,n,m,mm;

int main()
{
    f>>n>>m>>mm;
    for (i=1;i<=n;i++)
     {
         f>>x;
         sumaa[i]=sumaa[i-1]+x;
     }
     for (i=1;i<=n;i++)
     {
         f>>x;
         sumab[i]=sumab[i-1]+x;
     }
     for (i=mm;i<=n;i++)
      if ((100*(sumaa[i]-sumaa[i-mm]))/(sumab[i]-sumab[i-mm])>ma)
       ma=100*(sumaa[i]-sumaa[i-mm])/(sumab[i]-sumab[i-mm]);
      g<<ma/100<<'.'<<ma%100;
   f.close();
   g.close();
}