#include <bits/stdc++.h>
using namespace std;
const int maxN = 210;
double dp[maxN][maxN][maxN];
int main() {
  ios_base::sync_with_stdio(false);
  int N, L, K;
  cin >> N >> L >> K;
  double p[N + 1];
  int a[N + 1];
  p[0] = 1.0;
  for (int i = 1; i <= N; i++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  a[0] = K;
  for (int i = 1; i <= N; i++) {
    cin >> a[i];
    a[i]++;
  }
  dp[0][0][K] = 1.0;
  for (int i = 0; i < N; i++) {
    for (int j = 0; j <= i; j++) {
      for (int k = 0; k <= 200; k++) {
        if (dp[i][j][k] > 0.0) {
          int bag = min(200, k + a[i + 1]);
          dp[i + 1][j + 1][bag] += dp[i][j][k] * p[i + 1];
          dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i + 1]);
        }
      }
    }
  }
  double ans = 0.0;
  for (int j = L; j <= 200; j++)
    for (int k = j; k <= 200; k++) ans += dp[N][j][k];
  cout << fixed;
  cout.precision(9);
  cout << ans << endl;
  return 0;
}
