#include <bits/stdc++.h>
using namespace std;
const int N = 110;
int n;
double a[N], b[N];
double ans, last, now;
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    a[i] = x * 1.0 / 100;
  }
  for (int i = 1; i <= n; i++) b[i] = a[i];
  last = 1;
  for (int i = 1; i <= n; i++) last *= a[i];
  ans = last * n;
  for (int j = n + 1; j <= 200000; j++) {
    double p = 0;
    int q = 0;
    for (int i = 1; i <= n; i++) {
      double tmp = (b[i] + (1 - b[i]) * a[i]) / b[i];
      if (tmp > p) p = tmp, q = i;
    }
    b[q] = b[q] + (1 - b[q]) * a[q];
    now = last * p;
    ans += j * (now - last);
    last = now;
  }
  printf("%lf\n", ans);
  return 0;
}
