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)

#include <bits/stdc++.h>
using namespace std;
string xx[]={"7","5","3"};
int n,ans;
int main(){
	cin >> n;
	set<string> t;
	t.insert("");
	while(t.size()){
		set<string> p;
		for (auto y:t){
			if(y.size()>=9)continue;
			for(auto s:xx){
				string k = y+s;
				if(k.find('7')!=k.find('0'))
				if(k.find('5')!=k.find('0'))
				if(k.find('3')!=k.find('0'))
				if(stoi(k)<=n)ans++;
				p.insert(y+s);
			}
		}
		t = p;
	}
	cout << ans << endl;
}