#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  vector<int> p(n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &p[i]);
  }
  double ans = 0;
  vector<double> probtable(n, 1);
  for (int magic = 0; magic < 1000000; magic++) {
    double minprob =
        (1 - (1 - p[0] / 100.0) * probtable[0]) / (1 - probtable[0]);
    int minprobi = 0;
    for (int i = 1; i < n; i++) {
      double curratio =
          (1 - (1 - p[i] / 100.0) * probtable[i]) / (1 - probtable[i]);
      if (curratio < minprob) continue;
      minprob = curratio;
      minprobi = i;
    }
    if (magic < n) minprobi = magic;
    int j = minprobi;
    double curprobs = 1;
    for (int i = 0; i < n; i++) curprobs *= 1 - probtable[i];
    ans += 1 - curprobs;
    if (1 - curprobs < 1e-15) break;
    probtable[j] *= 1 - p[j] / 100.0;
    if (probtable[j] < 1e-20) probtable[j] = 0;
  }
  printf("%.10f\n", ans);
  return 0;
}
