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 <tuple>
#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;
ll N;
ll ans = 0;
ll memo;

bool check(ll x){
   string S = to_string(x);
   if(count(S.begin(),S.end(),'3') == 0 || count(S.begin(),S.end(),'5') == 0 || count(S.begin(),S.end(),'7') == 0){
      return 0;
   }else{
      return 1;
   }
}

void dfs(ll x){
   if(x > N){
      return;
   }
   if(check(x)){
      ans++;
   }
   if(x * 10 < 1000000000){
      dfs(x * 10 + 3);
      dfs(x * 10 + 5);
      dfs(x * 10 + 7);
   }
   return;
}

int main(){
 cin >> N;
 ans = 0;
 dfs(0);
 cout << ans << endl;

}