#include <bits/stdc++.h>
using namespace std;
double f[222][222][555];
int main() {
  int n, l, k;
  cin >> n >> l >> k;
  double p[222];
  for (int i = 0; i < n; ++i) {
    cin >> p[i];
    p[i] /= 100;
  }
  int a[222];
  for (int i = 0; i < n; ++i) cin >> a[i];
  f[0][0][k + 222] = 1;
  for (int i = 0; i < n; ++i)
    for (int u = 0; u < n; ++u)
      for (int j = 1; j <= 444; ++j) {
        f[i + 1][u + 1][min(j + a[i], 444)] += f[i][u][j] * p[i];
        f[i + 1][u][j] += f[i][u][j] * (1 - p[i]);
      }
  double ans = 0;
  for (int i = 222; i <= 444; ++i)
    for (int j = l; j <= n; ++j) ans += f[n][j][i];
  printf("%.10lf", ans);
  return 0;
}
