n = gets.to_i
i = 2
count2 = 0
count3 = 0
factorX = 0

while i ** 2 <= n
  while n % i == 0
    n /= i
    if i == 2
      count2 += 1
    elsif i == 3
      count3 += 1
    else
      factorX = i
    end
  end
  i += 1
end

if count3 > 0
  puts 3
elsif count2 >= 2
  puts 4
elsif factorX != 0
  puts factorX
else
  puts n
end