#include <bits/stdc++.h>
const long long maxn = 2000 + 10;
long long N, A, B, an[maxn], bn[maxn];
double pa[maxn], pb[maxn], f[maxn];
inline long long read() {
  long long f = 1, r = 0;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') {
      f = -1;
    }
    c = getchar();
  }
  while (isdigit(c)) {
    r = 10 * r + c - '0';
    c = getchar();
  }
  return f * r;
}
inline void write(long long x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) write(x / 10);
  putchar(x % 10 + '0');
}
inline void writesp(long long x) { write(x), putchar(' '); }
inline void writeln(long long x) { write(x), puts(""); }
void checkb(double adda, double addb) {
  for (long long i = 1; i <= N; ++i) {
    an[i] = an[i - 1], bn[i] = bn[i - 1], f[i] = f[i - 1];
    if (f[i - 1] + pa[i] - adda > f[i] + 1e-10) {
      f[i] = f[i - 1] + pa[i] - adda;
      an[i] = an[i - 1] + 1;
      bn[i] = bn[i - 1];
    }
    if (f[i - 1] + pb[i] - addb > f[i] + 1e-10) {
      f[i] = f[i - 1] + pb[i] - addb;
      bn[i] = bn[i - 1] + 1;
      an[i] = an[i - 1];
    }
    if (f[i - 1] + pb[i] - addb + pa[i] - adda - pa[i] * pb[i] > f[i] + 1e-10) {
      f[i] = f[i - 1] + pb[i] - addb + pa[i] - adda - pa[i] * pb[i];
      bn[i] = bn[i - 1] + 1;
      an[i] = an[i - 1] + 1;
    }
  }
}
double checka(double adda) {
  double l = 0, r = 1;
  for (long long i = 1; i <= 50; ++i) {
    double mid = (l + r) / 2.0;
    checkb(adda, mid);
    if (bn[N] > B) {
      l = mid;
    } else {
      r = mid;
    }
  }
  return r;
}
signed main() {
  N = read(), A = read(), B = read();
  for (long long i = 1; i <= N; ++i) {
    scanf("%lf", &pa[i]);
  }
  for (long long i = 1; i <= N; ++i) {
    scanf("%lf", &pb[i]);
  }
  double l = 0, r = 1, v;
  for (long long i = 1; i <= 50; ++i) {
    double mid = (l + r) / 2.0;
    v = checka(mid);
    if (an[N] > A) {
      l = mid;
    } else {
      r = mid;
    }
  }
  double ans = f[N] + l * A + v * B;
  printf("%.5lf\n", ans);
  return 0;
}
