#include <bits/stdc++.h>
using namespace std;
const int nmax = 105;
const double eps = 1e-10;
int n;
long double sol, all_taken;
long double taken[nmax], not_taken[nmax], p[nmax];
long double calc(int x) { return all_taken / taken[x] * not_taken[x] * p[x]; }
int main() {
  cin.sync_with_stdio(false);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  all_taken = 1.0;
  for (int i = 1; i <= n; i++) {
    taken[i] = p[i];
    not_taken[i] = 1.0 - p[i];
    all_taken *= p[i];
  }
  sol = all_taken * n;
  for (int i = n + 1; i <= 200000; i++) {
    long double best = -1.0;
    int guessed = 0;
    for (int j = 1; j <= n; j++)
      if (calc(j) > best) {
        best = calc(j);
        guessed = j;
      }
    double curr = calc(guessed);
    sol += curr * i;
    all_taken /= taken[guessed];
    taken[guessed] += not_taken[guessed] * p[guessed];
    all_taken *= taken[guessed];
    not_taken[guessed] *= (1.0 - p[guessed]);
  }
  cout << fixed << setprecision(8) << sol;
  return 0;
}
