#include <iostream>
#include <fstream>
#include <vector>
#include <iomanip>

using namespace std;

ifstream fin("secv3.in");
ofstream fout("secv3.out");

int main() {
    int l, u, n;
    fin >> n >> l >> u;
    vector<int> t(n);
    vector<int> b(n);
    for (int i = 0; i < n; i += 1) {
        fin >> t[i];
    }
    
    for (int i = 0; i < n; i += 1) {
        fin >> b[i];
    }
    
    int tSum = 0;
    int bSum = 0;
    double ans = 0;
    for (int i = 0; i < l; i += 1) {
        tSum += t[i];
        bSum += b[i];
    }
    
    // cerr << ans << endl;    
    for (int i = 0; i < (n-l+1); i += 1) {
        ans = max(ans, (double) (tSum/bSum));
        // cerr << fixed << setprecision(2) << (double) (tSum+tInc)/(bSum+bInc) << '\n';
        if (i+l < n) {
            tSum -= t[i];
            bSum -= b[i];
            tSum += t[i+l];
            bSum += b[i+l];
        }
    }
    
    fout << fixed << setprecision(2) << ans;
    
    return 0;
}