#include <bits/stdc++.h>
using namespace std;
const struct in_ {
} in;
template <typename T>
struct Proxy {
  Proxy(const T& t) : t_(t) {}
  const T& t_;
};
template <typename T>
Proxy<T> operator<<(const T& lhs, const in_& rhs) {
  return Proxy<T>(lhs);
}
template <typename T>
bool operator>>(const Proxy<T>& lhs, const vector<T>& rhs) {
  for (auto& a : rhs)
    if (lhs.t_ == a) return true;
  return false;
}
char _;
const int M = 205;
int n, l, k, ss[M];
bool vis[M][M][2 * M];
double p[M], dp[M][M][2 * M];
double help(int x, int w, int s) {
  if (x == n) {
    if (w >= l and s >= 200)
      return 1;
    else
      return 0;
  }
  if (vis[x][w][s]) return dp[x][w][s];
  vis[x][w][s] = true;
  return dp[x][w][s] = p[x] * help(x + 1, w + 1, min(s + ss[x], 400)) +
                       (1 - p[x]) * help(x + 1, w, s);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> l >> k;
  int x;
  for (int i = 0; i < n; i++) cin >> x, p[i] = x * 0.01;
  for (int i = 0; i < n; i++) cin >> ss[i];
  cout << fixed << setprecision(10) << help(0, 0, k + 200) << '\n';
  return 0;
}
