#include <bits/stdc++.h>
using namespace std;
double n, num = 0;
double ans = 0;
vector<int> v;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    v.push_back(a);
  }
  sort(v.begin(), v.end());
  for (int i = v[0];; i++) {
    for (int j = 0; j < n; j++) {
      if (i % v[j] == 0) {
        ans += i / v[j];
        num++;
      } else {
        break;
      }
    }
    if (num == n) {
      num = i;
      break;
    }
    num = 0;
    ans = 0;
  }
  double nas = num / ans;
  printf("%.1f\n", num / ans);
  return 0;
}
