N = gets.to_i

def f(x)
  return 0 if x < 10

  n = 1
  while 10 ** n <= x
    n += 1
  end

  v = 1
  0.upto(n - 1) do |i|
    u = Rational(x, 10.pow(i)).floor % 10
    v *= u
  end

  1 + f(v)
end

puts f(N)