#include <bits/stdc++.h>
using namespace std;
int N;
double S[100];
struct Pq {
  double p;
  int t;
  double i;
  Pq(const double _p, const int _t) : p(_p), t(_t), i(Increase()) {}
  double Guessed(const double _t) const { return 1.0 - pow(1.0 - p, _t); }
  double Increase() const { return Guessed(t + 1) / Guessed(t); }
  bool operator<(const Pq &o) const { return i < o.i; }
};
int main() {
  while (scanf("%d", &N) == 1) {
    for (int i = 0; i < N; i++) scanf("%lf", &S[i]), S[i] *= 0.01;
    priority_queue<Pq> pq;
    double now = 1.0;
    for (int i = 0; i < N; i++) {
      const Pq &p = Pq(S[i], 1);
      now *= p.Guessed(p.t);
      pq.push(p);
    }
    double ans = N * now;
    for (int i = N + 1;; i++) {
      Pq p = pq.top();
      pq.pop();
      const double pre = now;
      now *= p.Increase();
      pq.push(Pq(p.p, p.t + 1));
      ans += i * (now - pre);
      if (now == pre) break;
    }
    printf("%.9f\n", ans);
  }
  return 0;
}
