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 ll long long
#define int long long
#define ld long double
#define vi vector<int>
#define umap unordered_map
#define pii pair<int, int>
#define vpii vector<pii>
#define uset unordered_set
#define frw(i, a, b) for(auto i = (a); i < (b); i++)
#define bck(i, a, b) for(auto i = (a); i > (b); i--)
#define T() int testcases; cin >> testcases; frw(TC, 1, testcases + 1)
#define tez ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define endl "\n"
#define fi first
#define se second
#define pow asdihagsiduh
#define pub push_back
#define in insert
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(a) (int)(a.size())
#define sq(a) ((a) * (a))

#define trace(...) ZZ(#__VA_ARGS__, __VA_ARGS__)
template<typename Arg1> 
void ZZ(const char* name, Arg1&& arg1){
    cerr << name << " = " << arg1 << endl;
}
template<typename Arg1, typename... Args>
void ZZ(const char* names, Arg1&& arg1, Args&&... args){
    const char* comma = strchr(names + 1, ',');
    cerr.write(names, comma - names) << " = " << arg1;
    ZZ(comma, args...);
}

//console o/p without variable names
#define trace1(...) ZZ(__VA_ARGS__)
template<typename Arg1>
void ZZ(Arg1&& arg1){
    cerr << arg1 << endl;
}
template<typename Arg1, typename... Args>
void ZZ(Arg1&& arg1, Args&&... args){
    cerr << arg1 << ' ';
    ZZ(args...);
}

vi aux;

void gen(int n){
    if(n > 1e9) return;
    string s = to_string(n);
    sort(all(s));
    s.resize(unique(all(s)) - s.begin());
    if(sz(s) == 3)   aux.pub(n);
    gen(n * 10 + 3);
    gen(n * 10 + 5);
    gen(n * 10 + 7);
}

signed main(){
    tez
    gen(0);
    sort(all(aux));
    aux.resize(unique(all(aux)) - aux.begin());
    int n; cin >> n;
    cout << upper_bound(all(aux), n) - aux.begin();
}