#include <bits/stdc++.h>
const double eps = 1e-9;
using namespace std;
double f[2050], p[2050], q[2050];
int fa[2050], fb[2050];
int n, a, b;
void calc(double w1, double w2) {
  for (int i = 1; i <= n; i++) {
    f[i] = f[i - 1];
    fa[i] = fa[i - 1];
    fb[i] = fb[i - 1];
    if (f[i - 1] + p[i] - w1 > f[i]) {
      f[i] = f[i - 1] + p[i] - w1;
      fa[i] = fa[i - 1] + 1;
      fb[i] = fb[i - 1];
    }
    if (f[i - 1] + q[i] - w2 > f[i]) {
      f[i] = f[i - 1] + q[i] - w2;
      fa[i] = fa[i - 1];
      fb[i] = fb[i - 1] + 1;
    }
    if (f[i - 1] + p[i] + q[i] - p[i] * q[i] - w1 - w2 > f[i]) {
      f[i] = f[i - 1] + p[i] + q[i] - p[i] * q[i] - w1 - w2;
      fa[i] = fa[i - 1] + 1;
      fb[i] = fb[i - 1] + 1;
    }
  }
}
int main() {
  scanf("%d%d%d", &n, &a, &b);
  for (int i = 1; i <= n; i++) scanf("%lf", &p[i]);
  for (int i = 1; i <= n; i++) scanf("%lf", &q[i]);
  double l1 = 0, r1 = 1, l2, r2;
  while (l1 + eps < r1) {
    double mid1 = (l1 + r1) / 2;
    l2 = 0, r2 = 1;
    while (l2 + eps < r2) {
      double mid2 = (l2 + r2) / 2;
      calc(mid1, mid2);
      if (fb[n] > b)
        l2 = mid2;
      else
        r2 = mid2;
    }
    calc(mid1, r2);
    if (fa[n] > a)
      l1 = mid1;
    else
      r1 = mid1;
  }
  calc(r1, r2);
  printf("%.10lf\n", f[n] + a * r1 + b * r2);
  return 0;
}
