#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  long double p[n];
  long double a[n];
  for (int i = 0; i < n; i++) {
    int prob;
    scanf("%d", &prob);
    p[i] = 1.0 - prob / 100.0;
    a[i] = p[i];
  }
  long double pN = 0.0;
  long double ans = 0;
  for (int i = n; i <= 300000; i++) {
    long double k = 1.0, best = 0;
    for (int j = 0; j < n; j++) {
      k *= (1.0 - a[j]);
    }
    ans += (k - pN) * i;
    pN = k;
    int j_best = 0;
    for (int j = 0; j < n; j++) {
      if ((1.0 - a[j] * p[j]) / (1.0 - a[j]) > best)
        j_best = j, best = (1.0 - a[j] * p[j]) / (1.0 - a[j]);
    }
    a[j_best] *= p[j_best];
  }
  printf("%.8lf\n", (double)ans);
}
