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;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

int to753(int a,int d){
  int res=0;
  bool f7=false,f5=false,f3=false;
  int ten=1;
  rep(i,d){
    int r=a%3*2+3;
    res+=r*ten;
    if(r==3) f3=true;
    if(r==5) f5=true;
    if(r==7) f7=true;
    a/=3;
    ten*=10;
  }
  if(f3&&f5&&f7) return res;
  else return -1;
}

int main() {
  int n;
  cin>>n;
  int ans=0;
  int lim=753;
  int s=7000;
  int d=3;
  for(int t=5;d<10;t++){
    int a=to753(t,d);
    if(a==-1) continue;
    if(a>n) break;
    ans++;
    if(a==lim){
      lim=lim+s;
      s*=10;
      t=4;
      d++;
    }
  }
  cout<<ans<<endl;
  return 0;
}