#include <bits/stdc++.h>
int n, j;
long double p[110], ans, prob, d[110], maxi;
int main() {
  scanf("%d", &n);
  prob = 1;
  for (int i = 1; i <= n; i++)
    scanf("%Lf", p + i), p[i] /= 100, prob *= p[i], d[i] = p[i] = 1 - p[i];
  ans += n * prob;
  for (int i = n + 1; i <= n + 500000; i++) {
    j = 0;
    maxi = 0;
    for (int k = 1; k <= n; k++)
      if (prob / (1 - d[k]) * (1 - d[k] * p[k]) >= maxi) {
        maxi = prob / (1 - d[k]) * (1 - d[k] * p[k]);
        j = k;
      }
    d[j] *= p[j];
    ans += i * (maxi - prob);
    prob = maxi;
  }
  printf("%.12lf\n", (double)ans);
  return 0;
}
