#include <fstream>
#include <iomanip>


using namespace std;

ifstream fin ("secv3.in");

ofstream fout ("secv3.out");

int c[30005], t[30005], d[30005];

int main()

{

    int n, mn, mx, sum1 = 0, sum2 = 0;

    double ans = 0;

    fin >> n >> mn >> mx;

    for(int i = 1; i <= n; ++i) fin >> c[i];

    for(int i = 1; i <= n; ++i) fin >> t[i];

    int F = 1, L = 0;

    for(int i = 1; i <= mn; ++i) d[++L] = i, sum1 += c[d[L]], sum2 += t[d[L]];

    ans = max(ans, 1.0 * sum1 / sum2);

    for(int i = mn + 1; i <= n; ++i) {

        sum1 -= c[d[F]], sum2 -= t[d[F]];

        ++F, d[++L] = i;

        sum1 += c[d[L]], sum2 += t[d[L]];

        ans = max(ans, 1.0 * sum1 / sum2);

    }

    fout << fixed << setprecision(2) << ans;

    return 0;

}