# frozen_string_literal: true

L = 10**9 + 7

class Integer
  def fact
    (1..self).reduce(:*)
  end
end

def solve
  if A.any?(&:zero?)
    -1
  elsif A.max >= 4
    L
  else
    L % A.map { _1**_1.fact }.reduce(:*)
  end
end

N = gets.to_i
A = gets.split.map(&:to_i)
puts solve