#include <bits/stdc++.h>
using namespace std;
const int N = 201;
double dp[N][N][N], p[N], ans;
int a[N];
int main() {
  int i, j, n, l, k;
  cin >> n >> l >> k;
  for (i = 0; i < n; ++i) cin >> p[i], p[i] /= 100.0;
  for (i = 0; i < n; ++i) cin >> a[i], ++a[i];
  dp[0][0][min(k, n)] = 1.0;
  for (i = 0; i < n; ++i)
    for (j = 0; j <= i; ++j)
      for (k = 0; k <= n; ++k) {
        dp[i + 1][j + 1][min(n, k + a[i])] += dp[i][j][k] * p[i];
        dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i]);
      }
  for (j = l; j <= n; ++j)
    for (k = j; k <= n; ++k) ans += dp[n][j][k];
  printf("%.10lf", ans);
  return 0;
}
