#include <bits/stdc++.h>
using namespace std;
int x, N;
double a[110], p[110], q[110];
double P = 1.0, ret = 0.0;
int main() {
  scanf("%d", &N);
  for (int i = 1; i <= N; ++i) {
    cin >> x;
    p[i] = x / 100.0;
    q[i] = 1 - p[i];
    a[i] = q[i];
    P = P * p[i];
  }
  int M = 300000;
  ret = P;
  for (int t = N + 1; t <= M; ++t) {
    double ma = 0;
    int ind = 0;
    for (int i = 1; i <= N; ++i) {
      if ((1 - a[i] * q[i]) / (1 - a[i]) > ma) {
        ma = (1 - a[i] * q[i]) / (1 - a[i]);
        ind = i;
      }
    }
    P = P * ma;
    a[ind] *= q[ind];
    ret += P;
  }
  ret = (M + 1) * P - ret;
  printf("%.12lf", ret);
  return 0;
}
