#include <bits/stdc++.h>

using namespace std;

typedef long double ld;

struct jeg
{
        ld first;
        int second;
};

const int N = 2000 + 7;
int n;
int a;
int b;
ld p1[N];
ld p2[N];
jeg best[N][N]; /// poz

bool bigger(jeg a, jeg b)
{
        if (a.first != b.first)
                return a.first > b.first;
        else
                return a.second < b.second;
}

jeg max(jeg a, jeg b)
{
        if (bigger(a, b))
                return a;
        else
                return b;
}

void compute(ld c)
{
        for (int i = 1; i <= n; i++)
        {
                for (int x = 0; x <= a; x++)
                {
                        jeg one;
                        jeg two;

                        /// nu iau b
                                /// nu iau a
                                        one = best[i - 1][x];
                                /// iau a
                                        if (x >= 1)
                                                one = max(one, {best[i - 1][x - 1].first + p1[i], best[i - 1][x - 1].second});

                        /// iau b
                                /// nu iau a
                                        two = {best[i - 1][x].first + c + p2[i], best[i - 1][x].second + 1};
                                /// iau a
                                        if (x >= 1)
                                                two = max(two, {best[i - 1][x - 1].first + c + p2[i] + p1[i] - p1[i] * p2[i], best[i - 1][x].second + 1});
                        if (x == 0)
                                best[i][x] = one;
                        else
                        {
                                best[i][x] = max(two, one);
                        }
                }
        }
}


ld solve()
{
        compute(0);
       /** for (int i = 1; i <= n; i++)
        {
                for (int x = 0; x <= a; x++)
                {
                        cout << i << " " << x << " : " << best[i][x].first << "\n";
                }
        }
        exit(0);**/
        ld l = - (ld) 1e9;
        ld r = + (ld) 1e9;
        for (int i = 1; i <= 200; i++)
        {
                ld mid = (l + r) * 0.5;
                compute(mid);
                if (best[n][a].second <= b)
                        l = mid;
                else
                        r = mid;
        }
        compute(l);
        return {best[n][a].first - l * best[n][a].second};
}

int main()
{
        ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

       // freopen ("input", "r", stdin);

        cin >> n >> a >> b;
        for (int i = 1; i <= n; i++)
                cin >> p1[i];
        for (int i = 1; i <= n; i++)
                cin >> p2[i];
        cout << fixed << setprecision(6) << solve() << "\n";
}