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 Ruby (2.3.3) (judge verdict: Accepted)

N = gets.chomp.to_i
a = ['3','5','7']
ans = 0

#Nの桁数は9以下なので，3,4,...,9桁の整数について七五三数であるかを判定すればよい
3.step(9) {|i| #iは桁数
  ans += a.repeated_permutation(i).count {#3,5,7のいずれかを用いてi桁の整数を作り，条件を満たすものをカウントする
  #3,5,7を1回以上用いる＆N以下
  |b| b.uniq.size == 3 && b.join.to_i <= N
  }
}
puts ans