#include <bits/stdc++.h>
using namespace std;
int n;
long double p[110], g[110];
priority_queue<pair<long double, int> > q;
int main() {
  scanf("%d", &n);
  double now = 1;
  for (int i = 1; i <= n; i++) {
    cin >> p[i];
    p[i] /= 100;
    g[i] = p[i];
    now *= p[i];
    q.push(make_pair(1 - p[i], i));
  }
  long double ans = n;
  for (int round = 1; round <= 3000000; round++) {
    pair<long double, int> t = q.top();
    q.pop();
    int k = t.second;
    ans += t.first * now * round;
    now /= g[k];
    g[k] = g[k] + (1 - g[k]) * p[k];
    now *= g[k];
    q.push(make_pair(p[k] * (1 - g[k]) / g[k], k));
  }
  double tt = ans;
  printf("%.10f\n", tt);
  return 0;
}
