n = gets.to_i
a = gets.split(" ").map(&:to_i).sort!
max = a.max
b = []

(n-1).times do |i|
until a[n-1] % a[i] == 0
  a[n-1] += max
end
  max = a[n-1]
end

a.map{|j| b << a[n-1] / j}
p a[n-1] / b.inject(:+).to_f