# frozen_string_literal: true

require 'prime'

def solve
  N.divisors.select { |i| i > 2 }.min
end

# @see https://qiita.com/seinosuke/items/fde2e0471dcf937e5a09
class Integer
  def divisors
    return [1] if self == 1

    first, *rest = Prime.prime_division(self).map do |p, k|
      (0..k).map { |i| p**i }
    end
    first.product(*rest).map { |a| a.inject(&:*) }.sort
  end
end

N = gets.to_i

puts solve