#include <bits/stdc++.h>
using namespace std;
template <class T>
T abs(T x) {
  return x > 0 ? x : -x;
}
vector<int> paint;
vector<set<int>> pp;
int main() {
  int n, l, k;
  vector<vector<vector<double>>> sost(
      201, vector<vector<double>>(201, vector<double>(402, 0.0)));
  vector<int> ver(201), prize(201);
  cin >> n >> l >> k;
  for (int i = 0; i < n; i++) {
    cin >> ver[i];
  }
  for (int i = 0; i < n; i++) {
    cin >> prize[i];
  }
  sost[0][0][200 + k] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      for (int kk = 0; kk < 401; kk++) {
        sost[i + 1][j + 1][max(min(kk + prize[i], 400), 0)] +=
            sost[i][j][kk] * (ver[i] / 100.0);
        sost[i + 1][j][kk] += sost[i][j][kk] * ((100 - ver[i]) / 100.0);
      }
    }
  }
  double ans = 0;
  for (int i = l; i <= n; i++)
    for (int j = 200; j < 401; j++) {
      ans += sost[n][i][j];
    }
  cout << fixed << setprecision(6) << ans;
  return 0;
}
