import math
def ilog10(x):
  tmp=int(math.log10(x))
  # if x<10**tmp:
  #   return tmp-1
  return tmp
  

def MUL(x):
  res=1
  for i in range(ilog10(x)+1):
    res*=(x//(10**i))%10
  return res

def f(x):
  if x<10:
    return 0
  else:
    return 1+f(MUL(x))


print(f(int(input())))