require 'prime'
h = {
    4 => 3,
    6 => 5,
    8 => 7,
    9 => 7,
    10 => 7,
    12 => 11,
    14 => 13,
    15 => 7,
    16 => 7,
    18 => 8,
    20 => 19,
    21 => 19,
    22 => 7,
    24 => 23,
    25 => 23
}

n = gets.to_i
if h[n]
	puts h[n]
elsif (n-1)%8 == 0 && Prime.prime?(n-8)
	puts 14
else
	puts 8
end