#include <iostream>

using namespace std;
int cost[30005], time[30005], d[30005];
int main()
{
    freopen("secv3.in", "r", stdin);
    freopen("secv3.out", "w", stdout);
    int n, mn, mx, sum1 = 0, sum2 = 0;
    double ans = 0;
    scanf("%d%d%d", &n, &mn, &mx);
    for(int i = 1; i <= n; ++i) scanf("%d", &cost[i]);
    for(int i = 1; i <= n; ++i) scanf("%d", &time[i]);
    int F = 1, L = 0;
    for(int i = 1; i <= mn; ++i) d[++L] = i, sum1 += cost[d[L]], sum2 += time[d[L]];
    ans = max(ans, 1.0 * sum1 / sum2);
    for(int i = mn + 1; i <= n; ++i) {
        sum1 -= cost[d[F]], sum2 -= time[d[F]];
        ++F, d[++L] = i;
        sum1 += cost[d[L]], sum2 += time[d[L]];
        ans = max(ans, 1.0 * sum1 / sum2);
    }
    printf("%f", ans);
    return 0;
}