#include <bits/stdc++.h>
using namespace std;
const int lim = 201;
double P[lim][2 * lim][lim];
double p[lim];
int a[lim];
int n, l, k;
int main() {
  for (int i = 0; i < lim; i++) {
    for (int j = 0; j < 2 * lim; j++) {
      for (int k1 = 0; k1 < lim; k1++) {
        P[i][j][k1] = 0;
      }
    }
  }
  cin >> n >> l >> k;
  for (int i = 0; i < n; i++) {
    double x;
    cin >> x;
    p[i] = x / 100.0;
  }
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  P[0][k + lim][0] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < 2 * lim; j++) {
      for (int m = 0; m < lim - 1; m++) {
        P[i][min(j + a[i - 1], 2 * lim - 1)][m + 1] +=
            p[i - 1] * P[i - 1][j][m];
        P[i][j][m] += (1 - p[i - 1]) * P[i - 1][j][m];
      }
    }
  }
  double ans = 0;
  for (int j = lim; j < 2 * lim; j++) {
    for (int m = l; m < lim; m++) {
      ans += P[n][j][m];
    }
  }
  printf("%.10f\n", ans);
  return 0;
}
