#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-8;
const double PI = acos(-1.0);
const long long INF = 1e18;
const int mod = 1e9 + 7;
long long powmod(long long a, long long b) {
  long long res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
double a[110], p[110];
int main() {
  int n, x;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &x);
    a[i] = x / 100.0;
  }
  if (n == 1) return 0 * puts("1.00000000");
  double cur = 1.0;
  for (int i = 1; i <= n; i++) p[i] = 1 - a[i], cur *= a[i];
  double ans = n;
  for (int i = 1; i <= 500000; i++) {
    ans += 1 - cur;
    double tpcur = 0;
    int cs;
    for (int j = 1; j <= n; j++) {
      if (cur / (1 - p[j]) * (1 - p[j] * (1 - a[j])) > tpcur) {
        cs = j;
        tpcur = cur / (1 - p[j]) * (1 - p[j] * (1 - a[j]));
      }
    }
    cur = cur / (1 - p[cs]) * (1 - p[cs] * (1 - a[cs]));
    p[cs] *= (1 - a[cs]);
  }
  printf("%.12f\n", ans);
  return 0;
}
