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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

// C - 755
#include <bits/stdc++.h>
using namespace std;

int N;//limit value
int Digit;//limit number of digit
int Count;//anser

void dfs(int x, int depth){
	if(x > N) return;//exceeded value limit?

	set<int> s;
	for(int a=x; a && s.size()<3; a/=10) s.insert(a%10);
	if(s.size() == 3) Count++;//{3,5,7}.size()==3

	if(depth >= Digit) return;//limit of digits?

	dfs(x*10+3, depth+1);
	dfs(x*10+5, depth+1);
	dfs(x*10+7, depth+1);
}

int main(){
	string s; cin>>s;
	Digit = s.size();
	N = stoi(s);
	dfs(0, 0);
	cout<< Count <<endl;
}