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<iostream>
#include<iomanip>
#include<math.h>
#include<algorithm>
#include<utility>
#include<functional>
#include<queue>
#include<string.h>
#include<string>
#include<set>
#include<map>
#include<vector>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> PA;
const int MOD = 1000000007;
const ll INF=2e18;

ll N,M;
ll a[100010],b[100010];
ll num[10];
string s;
ll F(string now){
  if(now.length()==s.length()){
    ll n=stol(now);
    if(n>N){
      return 0;
    }
    map<ll,ll> mp;
    for(ll i=0;i<now.length();i++){
      mp[now[i]-'0']++;
    }
    if(mp[3]>0 && mp[5]>0  && mp[7]>0 ){
      return 1;
    }
    return 0;
  }
  return F(now+'3')+F(now+'5')+F(now+'7');
}
int main(){
    cin>>N;
    s=to_string(N);
    ll ans=F("");
    for(ll i=0;i<s.length();i++){
      ll n=pow(10,i);
      ans+=F(to_string(n));
    }
    cout<<ans;
    return 0;
}