Problem:
Score : 300 points

Problem 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.

Constraints

1 \leq N < 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).

Sample Input 1

575

Sample Output 1

4

There are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and 573.

Sample Input 2

3600

Sample Output 2

13

There are 13 Shichi-Go-San numbers not greater than 3600: the above four numbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.

Sample Input 3

999999999

Sample Output 3

26484

Solution in Python (3.4.3) (judge verdict: Accepted)

N = input()

l = len(N)
ans = 0
#各桁を「数字無し（０）」「７（１）」「５（２）」「３（３）」で記述するような4進数を作る
for n in range(1, 4**l):
  n4 = ""
  while n > 0:
    mod = n % 4
    n4 = str(mod) + n4
    n //= 4
  
  if "0" in n4:
    continue
  
  if ("1" in n4) and ("2" in n4) and ("3" in n4):
    n4_10 = ""
    for i in range(len(n4)):
      if n4[i] == "1":
        n4_10 = n4_10 + "7"
      elif n4[i] == "2":
        n4_10 = n4_10 + "5"
      else:
        n4_10 = n4_10 + "3"
    if int(n4_10) <= int(N):
      ans += 1

print(ans)