#include <bits/stdc++.h>
using namespace std;
const double INF = (int)1e9;
const int T = (int)1e6;
const int N = 111;
int n;
double p[N];
double q[N];
int r[N];
double ans = 1;
int a[N];
int choose() {
  int v = -1;
  double val = INF;
  for (int i = 0; i < n; i++) {
    double w = (1 - q[i]) / (1 - q[i] * (1 - p[i]));
    if (w < val) {
      val = w;
      v = i;
    }
  }
  return v;
}
void addOne() {
  int v = choose();
  a[v]++;
  q[v] *= (1 - p[v]);
  double Q = 1;
  for (int i = 0; i < n; i++) Q *= 1 - q[i];
  ans += 1 - Q;
  return;
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &r[i]);
    p[i] = r[i] / 100.;
    q[i] = 1;
  }
  for (int it = 0; it < T; it++) addOne();
  printf("%.10lf\n", ans);
  return 0;
}
