#include <bits/stdc++.h>
#pragma warning(disable : 4996)
using namespace std;
using ld = long double;
template <class T>
using Table = vector<vector<T>>;
int main() {
  int N;
  cin >> N;
  vector<ld> pers;
  for (int i = 0; i < N; ++i) {
    ld a;
    cin >> a;
    a /= 100;
    pers.push_back(a);
  }
  vector<ld> livepers(N, 1);
  ld ans = 0;
  for (int i = 0; i < 1000000; ++i) {
    ld clearper = 1;
    for (int j = 0; j < N; ++j) {
      clearper *= (1 - livepers[j]);
    }
    ans += 1 - clearper;
    vector<ld> sucpers(N);
    for (int j = 0; j < N; ++j) {
      sucpers[j] = (1 - livepers[j] * (1 - pers[j])) / (1 - livepers[j]);
    }
    int select = max_element(sucpers.begin(), sucpers.end()) - sucpers.begin();
    livepers[select] *= 1 - pers[select];
  }
  cout << fixed << setprecision(22) << ans << endl;
  return 0;
}
