#include <bits/stdc++.h>
using namespace std;
double p[111], q[111];
int main() {
  int n;
  cin >> n;
  for (int i = 0, u; i < n; i++) {
    scanf("%d", &u);
    p[i] = u / 100.0;
    q[i] = 1;
  }
  double ans = 0;
  while (1) {
    int now = 0;
    double tmp = 1;
    for (int i = 0; i < n; i++) {
      if (q[i] * p[i] * (1 - q[now]) > q[now] * p[now] * (1 - q[i])) now = i;
      tmp *= 1 - q[i];
    }
    ans += 1 - tmp;
    q[now] *= (1 - p[now]);
    if (1 - tmp < 1e-10) break;
  }
  printf("%.6lf\n", ans);
  return 0;
}
