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)

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
#define cinf(n,x) for(int i=0;i<(n);i++)cin>>x[i];
#define max3(a,b,c) max(max(a,b),c)
#define min3(a,b,c) min(min(a,b),c)
#define ft first
#define sc second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(),(v).end()
#define mod 1000000007
using namespace std;
typedef long long ll;
template<class T> using V=vector<T>;
using Graph = vector<vector<int>>;
using P=pair<ll,ll>;
typedef unsigned long long ull;
typedef long double ldouble;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }

ll f(ll n){
    ll k=1;
    rep(i,n) k*=3;
    return k;
}

int main(){
    ll b;
    cin>>b;
    string s;
    s=to_string(b);
    ll n=s.size();
    ll ans=0;
    for(int i=0;i<n;i++){
        ll m=f(i+1);
        for(int j=0;j<m;j++){
            ll a=j;
            V<bool> ok(3,0);
            string t;
            for(int k=0;k<i+1;k++){
                if(a%3==0){
                    t+='3';
                    ok[0]=1;
                }
                else if(a%3==1){
                    t+='5';
                    ok[1]=1;
                }
                else if(a%3==2){
                    t+='7';
                    ok[2]=1;
                }
                a/=3;
            }
            ll u=stoll(t);
            if(u<=b&&ok[0]&&ok[1]&&ok[2]) ans++;
        }
    }
    cout<<ans<<endl;
}