output_description: Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
attempt: N = int(input())
  def dfs(s): # 文字列 s で始まる七五三数の個数 
  if int(s) > N:
  	return 0
  ret = 1 if all(s.count(c) > 0 for c in '753') else 0 # s 自体が七五三数なら +1 
  for c in '753':
    ret += dfs(s + c)
    return ret
  print(dfs('0')) # 本当は dfs('') と書きたいが 4 行目でのエラーを防ぐため仕方なく
  
problem_description: Statement
  
  You are given an integer N. Among the integers between 1 and N (inclusive),
  how many _Shichi-Go-San numbers_ (literally "Seven-Five-Three numbers") are
  there?
  
  Here, a Shichi-Go-San number is a positive integer that satisfies the
  following condition:
  
    * When the number is written in base ten, each of the digits `7`, `5` and `3` appears at least once, and the other digits never appear.
samples: [{"input": "575", "output": "4\n    \n\nThere are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and\n573.\n\n* * *"}, {"input": "3600", "output": "13\n    \n\nThere are 13 Shichi-Go-San numbers not greater than 3600: the above four\nnumbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.\n\n* * *"}, {"input": "999999999", "output": "26484"}]