# include <bits/stdc++.h>
using namespace std;
ifstream fi("secv3.in");
ofstream fo("secv3.out");
const int nmax = 3e4 + 5;
int s[nmax],v[nmax],k,l,n,g;
double a[nmax];
deque < int > Q;
bool corespunde(double x)
{
    while (!Q.empty()) Q.pop_front();
    a[0]=0;
    for (int i=1;i<=n;++i) a[i] = a[i-1] + s[i] - x * v[i];
    double M=-1e15;
    for (int i=1;i<=n-k+1;++i)
    {
        while (!Q.empty() && a[i]<=a[Q.back()]) Q.pop_back();
        Q.push_back(i);
        while (!Q.empty() && i-g>Q.front()) Q.pop_front();
        if (!Q.empty() && a[i+k-1]-a[Q.front()]>M) M=a[i+k-1]-a[Q.front()];
    }
    return (M > 0);
}
int main(void)
{
    fi>>n>>k>>l;g=l-k+1;
    for (int i=1;i<=n;++i) fi >> s[i];
    for (int i=1;i<=n;++i) fi >> v[i];
    double p=0,u=*max_element(s+1,s+1+n);
    while (p<=u)
    {
        double m  = (p+u)/2.0;
        if (corespunde(m)) p=m+0.001;else u=m-0.001;
    }
    return fo << fixed << setprecision(2) << p << '\n',0;
}