#include <bits/stdc++.h>
using namespace std;
long double dp[202][202][202];
int a[202];
long double p[202];
int main() {
  ios::sync_with_stdio(0);
  cout << fixed << setprecision(8);
  int n, l, k;
  cin >> n >> l >> k;
  for (int i = 1; i <= n; i++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  for (int j = 1; j <= n; j++) {
    cin >> a[j];
    a[j]++;
  }
  dp[0][0][k] = 1;
  for (int i = 1; i <= n; i++) {
    dp[i][0][k] += dp[i - 1][0][k] * (1 - p[i]);
    for (int j = 1; j <= i; j++) {
      for (int st = 0; st <= 200; st++) {
        int newst = min(200, st + a[i]);
        dp[i][j][st] += dp[i - 1][j][st] * (1 - p[i]);
        dp[i][j][newst] += dp[i - 1][j - 1][st] * p[i];
        if (i == 1 && j == 1 && !newst) int abc = 0;
      }
    }
  }
  long double ans = 0;
  for (int i = l; i <= n; i++) {
    for (int j = i; j <= 200; j++) ans += dp[n][i][j];
  }
  cout << ans;
  return 0;
}
