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=int(input())
nana=[7,5,3]
def check(x):
    s=str(x)
    d=1 if all(s.count(str(nana[i]))>=1 for i in range(3) ) else 0
    return (d and x<=n)

def dfs(x):
    res=0
    if x>n:
        return 0
    if check(x):
        res+=1
    for i in range(3):
        res+=dfs(10*x+nana[i])
    return res
 
print(dfs(0))