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

def powmod(a,k,m)
  return 1 if k == 0
  t = powmod(a, k / 2, m)
  t = t * t % m
  t = t * a % m if k.odd?
  return t
end

def prime?(n)
  return false if n<2
  return true if n<4
  return false if n.even?
  d = n-1
  d >>= 1 while d.even?
  100.times do
    a = rand(n-1) + 1
    y = powmod(a, d, n)
    t = d
    while t != n-1 and y != 1 and y != n-1
      y = (y*y) % n
      t <<= 1
    end
    return false if y!=n-1 and t.even?
  end
  return true
end

n=gets.chomp.to_i
p m[n]?m[n]:(n%8==1&&prime?(n-8))?14:8