#include <bits/stdc++.h>
using namespace std;
int n, k;
double a[200], p[200];
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &k);
    p[i] = k * 0.01;
  }
  for (int i = 0; i < n; i++) {
    a[i] = 1.0;
  }
  double l = 0.0;
  double ans = 0.0;
  for (int it = 1; it <= 1000000; it++) {
    double pr = 1.0;
    for (int i = 0; i < n; i++) {
      pr *= (1.0 - a[i]);
    }
    ans += pr;
    int u = 0;
    double v = 0.0;
    if (it <= n) {
      u = it - 1;
    } else {
      for (int i = 0; i < n; i++) {
        double t = pr / (1.0 - a[i]) * (1.0 - (a[i] * (1.0 - p[i])));
        if (t > v) {
          u = i;
          v = t;
        }
      }
    }
    a[u] *= (1.0 - p[u]);
    l = pr;
  }
  ans = 1000000 * l - ans;
  printf("%.10f\n", ans);
  return 0;
}
