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: Wrong Answer)

import itertools
import copy as cp
X = int(input())
X_l = len(str(X))
n = ['3','5','7']
comb = ['357']
all_comb = []
all_ans = []
for i in range(X_l - 3):
  tmp_comb = cp.copy(comb)
  for co in tmp_comb:
    for key in n:
      newco = cp.copy(co)
      newco = newco + key
      newco = sorted(newco)
      comb.append(''.join(newco))
comb = list(set(comb))
for co in comb:
  co = [i for i in co]
  for c in itertools.permutations(co, len(co)):
    all_comb.append(c)
for nums in list(set(all_comb)):
  num = int(''.join(nums))
  if num < X:
    all_ans.append(num)
print(len(all_ans))