#include <bits/stdc++.h>
using namespace std;
const int maxn = 112;
int n;
double ans;
double p[maxn], q[maxn];
int Get_choose() {
  double w = 1e12, v = -1;
  for (int i = 1; i <= n; ++i) {
    double now = (1 - q[i]) / (1 - q[i] * (1 - p[i]));
    if (now < w) {
      w = now;
      v = i;
    }
  }
  return v;
}
void Get_add() {
  int v = Get_choose();
  q[v] *= (1 - p[v]);
  double Q = 1.0;
  for (int i = 1; i <= n; ++i) Q *= (1 - q[i]);
  ans += 1 - Q;
}
int main() {
  scanf("%d", &n);
  ans = 1.0;
  for (int i = 1; i <= n; ++i) {
    scanf("%lf", &p[i]);
    p[i] /= 100.0;
    q[i] = 1;
  }
  for (int i = 1; i <= 300000; ++i) Get_add();
  printf("%.10lf\n", ans);
  return 0;
}
