#include <bits/stdc++.h>
using namespace std;
double f[222][222][445];
double pro[222];
int n, l, k;
int main() {
  cin >> n >> l >> k;
  for (int i = 0; i < n; ++i) {
    int first;
    scanf("%d", &first);
    pro[i] = first / 100.;
  }
  f[0][0][222 + k] = 1.;
  for (int i = 0; i < n; ++i) {
    int val;
    scanf("%d", &val);
    for (int win = 0; win <= i; ++win) {
      for (int space = -200; space <= 200; ++space) {
        if (val == -1) {
          f[i + 1][win + 1][222 + space - 1] += f[i][win][222 + space] * pro[i];
        } else {
          f[i + 1][win + 1][222 + min(200, space + val)] +=
              f[i][win][222 + space] * pro[i];
        }
        f[i + 1][win][222 + space] += f[i][win][222 + space] * (1 - pro[i]);
      }
    }
  }
  double ans = 0;
  for (int wins = l; wins <= n; ++wins) {
    for (int space = 0; space <= 200; ++space) {
      ans += f[n][wins][222 + space];
    }
  }
  printf("%0.9lf\n", ans);
  return 0;
}
