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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Data.List

main=do
    n<-readLn::IO Int
    print $ length $ filter (<=n) $ map read g

g = u $ sort $ concatMap m $ concatMap k [3..9]

u [x] = [x]
u (a:b:x)
    | a==b = u (b:x)
    | otherwise = a:u (b:x)

k n = [(a,b,c)|a<-[1..n-2],b<-[1..n-a-1],c<-[1..n-a-b]]

m :: (Int,Int,Int)->[String]
m (0,0,0) = [[]]
m (a,0,0) = map ('3':) (m (a-1,0,0))
m (0,b,0) = map ('5':) (m (0,b-1,0))
m (0,0,c) = map ('7':) (m (0,0,c-1))
m (0,b,c) = map ('5':) (m (0,b-1,c)) ++ map ('7':) (m (0,b,c-1))
m (a,0,c) = map ('3':) (m (a-1,0,c)) ++ map ('7':) (m (a,0,c-1))
m (a,b,0) = map ('3':) (m (a-1,b,0)) ++ map ('5':) (m (a,b-1,0))
m (a,b,c) = map ('3':) (m (a-1,b,c)) ++ map ('5':) (m (a,b-1,c)) ++ map ('7':) (m (a,b,c-1))