#include <bits/stdc++.h>
using namespace std;
int n;
long double p[((int)110)], lst[((int)110)], now = 1, ans;
priority_queue<pair<long double, int> > s;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> p[i];
    p[i] /= (long double)100;
    now *= p[i];
    s.push({(long double)(1 - (1 - p[i]) * (1 - p[i])) / p[i], i});
    lst[i] = p[i];
  }
  ans = now * n;
  for (int i = n + 1; i < ((int)501 * 1000); i++) {
    long double inc = s.top().first;
    int x = s.top().second;
    s.pop();
    ans += now * (inc - 1) * i;
    now *= inc;
    lst[x] = 1 - (1 - p[x]) * (1 - lst[x]);
    s.push({(1 - (1 - p[x]) * (1 - lst[x])) / lst[x], x});
  }
  cout << fixed << setprecision(16) << ans << "\n";
  return 0;
}
