#include <bits/stdc++.h>
using namespace std;
long double p[111];
struct node {
  long double curp;
  long double nextp;
  long double _p;
  int id;
  bool operator<(const node &other) const {
    return nextp / curp < other.nextp / other.curp;
  }
};
int main() {
  int n;
  cin >> n;
  priority_queue<node> que;
  for (int i = 1; i <= n; i++) {
    int pp;
    scanf("%d", &pp);
    p[i] = pp / 100.0;
    node nd;
    nd._p = 1 - p[i];
    nd.curp = p[i];
    nd.nextp = 1 - (1 - p[i]) * nd._p;
    nd.id = i;
    que.push(nd);
  }
  long double ans = 0.0;
  sort(p + 1, p + n + 1);
  reverse(p + 1, p + n + 1);
  long double pend = 1.0;
  for (int i = 1; i <= n; i++) {
    pend *= p[i];
  }
  ans += pend * n;
  for (int k = n + 1; k <= 1000000; k++) {
    node tp = que.top();
    que.pop();
    long double tmp = pend;
    pend *= tp.nextp / tp.curp;
    tp.curp = tp.nextp;
    tp.nextp = 1 - (1 - tp.curp) * tp._p;
    que.push(tp);
    ans += k * (pend - tmp);
  }
  double re = ans;
  printf("%.10f\n", re);
  return 0;
}
