#include <bits/stdc++.h>
using namespace std;
int n, l, k;
double dp[201][201][201];
int a[201];
double p[201];
int main() {
  scanf("%d %d %d", &n, &l, &k);
  for (int(i) = 0; (i) < (int)(n); (i)++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  for (int(i) = 0; (i) < (int)(n); (i)++) scanf("%d", &a[i]);
  dp[0][0][0] = 1.0;
  for (int(i) = 0; (i) < (int)(n); (i)++)
    for (int(j) = 0; (j) < (int)(i + 1); (j)++)
      for (int(m) = 0; (m) < (int)(n + 1); (m)++) {
        int c = a[i] + 1;
        dp[i + 1][j + 1][min(m + c, n)] += dp[i][j][m] * p[i];
        dp[i + 1][j][m] += dp[i][j][m] * (1.0 - p[i]);
      }
  double ans = 0.000;
  for (int(i) = 0; (i) < (int)(n + 1); (i)++)
    for (int(j) = 0; (j) < (int)(n + 1); (j)++)
      if (i >= l && k + j - i >= 0) ans += dp[n][i][j];
  cout << ans << endl;
}
