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;
typedef long long ll;
ll ans = 0;
ll n;
void f (string s);
string s357 = "357";
int main (){
	cin >> n;
	f("0");
	cout<<ans<<endl;
	return 0;
}
void f (string s){
	ll num = atol(s.c_str());
	if(n<num)
		return;
	int check[3]={0};
	for(int i=0;i<s.size();i++){
		if(s[i]=='3')
			check[0]=1;
		if(s[i]=='5')
			check[1]=1;
		if(s[i]=='7')
			check[2]=1;
	}
	if(check[0]&&check[1]&&check[2])
		ans++;
		//cout<<s<<endl;
	for(int i=0;i<3;i++){
		f(s+s357[i]);
	}
}