#include <bits/stdc++.h>
using namespace std;
using Mem = vector<vector<vector<double>>>;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, I, k;
  vector<double> P(1, 0.0);
  vector<int> prizes(1, 0);
  Mem M;
  cin >> n >> I >> k;
  k = min(n, k);
  int p_i, a_i;
  for (int j = 0; j < n; ++j) {
    cin >> p_i;
    P.push_back((double)p_i / 100);
  }
  for (int j = 0; j < n; ++j) {
    cin >> a_i;
    prizes.push_back(a_i);
  }
  M.assign(n + 1, vector<vector<double>>(n + 1, vector<double>(2 * n + 1, 0)));
  M[0][0][k + n] = 1;
  for (int t = 1; t <= n; t++) {
    for (int w = 0; w <= t - 1; w++) {
      for (int c = k - w; c <= n; c++) {
        M[t][w][c + n] += (1 - P[t]) * M[t - 1][w][c + n];
        M[t][w + 1][min(c + prizes[t], n) + n] += P[t] * M[t - 1][w][c + n];
      }
    }
  }
  double res = 0;
  for (int w = I; w <= n; w++) {
    for (int c = 0; c <= n; c++) {
      res += M[n][w][c + n];
    }
  }
  cout << res << endl;
  return 0;
}
