class Integer
    def prime?
      n = self.abs()
      return true if n == 2
      return false if n == 1 || n & 1 == 0
      d = n-1
      d >>= 1 while d & 1 == 0
      20.times do 
        a = rand(n-2) + 1
        t = d
        y = ModMath.pow(a,t,n)
        while t != n-1 && y != 1 && y != n-1
          y = (y * y) % n
          t <<= 1
        end
        return false if y != n-1 && t & 1 == 0
      end
      return true
    end
  end
  
  module ModMath
    def ModMath.pow(base, power, mod)
      result = 1
      while power > 0
        result = (result * base) % mod if power & 1 == 1
        base = (base * base) % mod
        power >>= 1;
      end
      result
    end
  end
$dx = [1, 0, -1, 0]
$dy = [0, 1, 0, -1]
def find(cx, cy, w)
    t = cy * w + cx
    4.times do |i|
        x = cx + $dx[i]
        y = cy + $dy[i]
        t = y * w + x
        next if x < 0 || x >= w || y < 0 || t + 1 > $n || $b[t]
        return true if t + 1 == $n
        $b[t] = true
        check = find(x, y, w)
        $b[t] = false
        return true if check
    end
    return false
end
$n = gets.to_i
if $n <= 25
    $b = Array.new($n)
    25.times do |j|
        $b[j] = (j + 1).prime?
    end
    25.times do |w|
        w += 1
        if find(0, 0, w)
            puts w
            exit
        end
    end
end
if $n % 8 == 1 && ($n - 8).prime?
    puts 14
else
    puts 8
end