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)

def shichigo(s):
    if '3' not in s:
        return False
    if '5' not in s:
        return False
    if '7' not in s:
        return False
    x = s.replace('3','').replace('5','').replace('7','')
    if x=='':
        return True
    return False

n = input()

l = [[] for i in range(len(n))]
l[0] = ['3','5','7']
for i in range(1,len(l)):
    for j in range(len(l[i-1])):
        l[i].append('3'+l[i-1][j])
        l[i].append('5'+l[i-1][j])
        l[i].append('7'+l[i-1][j])

ans = 0
for i in range(len(l)):
    for j in range(len(l[i])):
        if int(n) >= int(l[i][j]):
            if shichigo(l[i][j]):
                ans += 1

print(ans)