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>

#define REP(i, n) for(int (i)=0;(i)<(n);++(i))
#define REPV(iter, v) for(auto (iter)=(v).begin(); (iter)!=(v).end();++(iter))
#define ALL(v) (v).begin(),(v).end()

#define MOD 1000000007

using namespace std;

typedef long long ll;

int main()
{
    ll N;
    cin >> N;
    queue<string> q;
    vector<string> numV;
    numV.push_back("3");
    numV.push_back("5");
    numV.push_back("7");
    q.push("357");
    q.push("375");
    q.push("537");
    q.push("573");
    q.push("735");
    q.push("753");
    ll ans = 0;
    map<string, bool> countMap;
    while(!q.empty())
    {
        string s = q.front();
        ll p = stoll(s);
        q.pop();
        if (p <= N) 
        {
            ans++;
            REPV(it, numV)
            {
                REP(i, s.size() + 1)
                {
                    string pushS;
                    if (i == 0)
                    {
                        pushS = *it + s;
                    }
                    else if (i == s.size())
                    {
                        pushS = s + *it;
                    }
                    else
                    {
                        pushS = s.substr(0, i) + *it + s.substr(i, s.size() - 1);
                    }
                    if (countMap.find(pushS) == countMap.end())
                    {
                        countMap[pushS] = true;
                        q.push(pushS);
                    }
                }
            }
        }
    }

    cout << ans << endl;
}