#include <bits/stdc++.h>
using namespace std;
int bitct(long long r) { return r == 0 ? 0 : (bitct(r >> 1) + (r & 1)); }
long long gcd(long long x, long long y) { return x ? gcd(y % x, x) : y; }
template <typename T>
ostream& operator<<(ostream& o, vector<T> v) {
  o << "[";
  int i = 0, s = v.size();
  for (; i + 1 < s; i++) o << v[i] << ", ";
  if (s) o << v[i];
  o << "]";
  return o;
}
template <typename K, typename V>
ostream& operator<<(ostream& o, unordered_map<K, V> m) {
  o << "{";
  for (auto i : m) o << i.first << " -> " << i.second << ", ";
  o << "}";
  return o;
}
template <typename K, typename V>
ostream& operator<<(ostream& o, map<K, V> m) {
  o << "{";
  for (auto i : m) o << i.first << " -> " << i.second << ", ";
  o << "}";
  return o;
}
template <typename K, typename V>
ostream& operator<<(ostream& o, set<K> m) {
  o << "{";
  for (auto i : m) o << i << ", ";
  o << "}";
  return o;
}
template <typename K, typename V>
ostream& operator<<(ostream& o, unordered_set<K> m) {
  o << "{";
  for (auto i : m) o << i << ", ";
  o << "}";
  return o;
}
long long choose(long long n, long long q) {
  if (n == 0 || q == 0) return 1;
  if (q == 1)
    return n;
  else
    return (choose(n, q - 1) * (n - q + 1) / q);
}
int main() {
  ios_base::sync_with_stdio(false);
  long long N;
  cin >> N;
  vector<long double> prob;
  for (int i = 0; i < N; i++) {
    long long x;
    cin >> x;
    prob.push_back((0.0 + x) / 100.0);
  }
  vector<long double> pdone = prob;
  long double out = 0;
  long double done = 0;
  long long turn = N;
  while (done < .999999999999999) {
    int worst = -1;
    long double wval = -10.0;
    long double olddone = done;
    done = 1.0;
    for (int i = 0; i < N; i++) {
      done *= pdone[i];
      long double inc = ((1.0 - pdone[i]) * prob[i]) / pdone[i];
      if (inc > wval) {
        wval = inc;
        worst = i;
      }
    }
    out += turn++ * (done - olddone);
    pdone[worst] = (1.0 - pdone[worst]) * prob[worst] + pdone[worst];
  }
  out += (1.0 - done) * turn;
  cout.precision(12);
  cout << out << endl;
}
