#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, w, l;
  cin >> n >> l >> w;
  long double p[n + 1];
  long long int b[n + 1];
  for (long long int i = 1; i <= n; i++) {
    cin >> p[i];
    p[i] /= 100;
  }
  for (long long int i = 1; i <= n; i++) {
    cin >> b[i];
    b[i]++;
  }
  long double a[n + 1][n + 1][n + 1];
  for (long long int i = 0; i <= n; i++) {
    for (long long int j = 0; j <= n; j++) {
      for (long long int k = 0; k <= n; k++) {
        a[i][j][k] = 0;
      }
    }
  }
  long double x, y;
  long long int z = 0;
  if (w > n) w = n;
  a[0][0][w] = 1;
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = 0; j <= i; j++) {
      for (long long int k = 0; k <= n; k++) {
        z = b[i];
        z += k;
        if (z > n) z = n;
        if (j > 0) a[j][i - j][z] += ((a[j - 1][i - j][k]) * (p[i]));
        if ((i - j) > 0)
          a[j][i - j][k] += ((a[j][i - j - 1][k]) * (1.0 - p[i]));
      }
    }
  }
  long double ans = 0.0;
  for (long long int i = 0; i <= n; i++) {
    for (long long int j = 0; j <= n; j++) {
      for (long long int k = 0; k <= n; k++) {
        if ((k >= i) && (i >= l) && ((i + j) == n)) {
          ans += a[i][j][k];
        }
      }
    }
  }
  cout << fixed << setprecision(6) << ans;
}
