#include <bits/stdc++.h>
using namespace std;
int a[205];
bool vis[205][205][405];
long double n, l, k, p[205], dp[205][205][405];
long double solve(int idx, int w, int c) {
  if (idx == n) return w >= l && c > -1;
  long double &ans = dp[idx][w][c];
  if (vis[idx][w][c]) return ans;
  vis[idx][w][c] = 1;
  ans += p[idx] * solve(idx + 1, w + 1, min(c + a[idx], 400));
  ans += (1.0 - p[idx]) * solve(idx + 1, w, c);
  return ans;
}
int main() {
  ios::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  cin >> n >> l >> k;
  for (int i = 0; i < n; i++) cin >> p[i], p[i] /= 100.0;
  for (int i = 0; i < n; i++) cin >> a[i];
  cout << solve(0, 0, k) << endl;
  return 0;
}
