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: Time Limit Exceeded)

#include <bits/stdc++.h>
using namespace std;
/*void m_cal(int n, int digit, int &ans)
{
    int upper = n / pow(10, digit - 1);
    if (upper > 7) //最上位が8,9
        ans += (pow(3, digit - 3) * digit * (digit - 1) * (digit - 2));
    else if (upper > 5) //最上位が6.7
        ans += (2 * pow(3, digit - 3) * (digit - 1) * (digit - 2));
    else if (upper > 3) //最上位が4,5
        ans += (pow(3, digit - 3) * (digit - 1) * (digit - 2));
    else //最上位が1,2,3
        ans += (pow(3, digit - 4) * (digit - 1) * (digit - 2) * (digit - 3));
    if (upper == 3 || upper == 5 || upper == 7)
    {
        m_cal(n - pow(upper, digit - 1), digit - 1, ans);
    }
}*/
int main()
{
    int n, digit(1), ans(0);
    cin >> n;
    int a3, a5, a7, number;
    for (int i = 357; i <= n; ++i)
    {
        a3 = 0, a5 = 0, a7 = 0, number = i;
        bool is357 = true;
        while (number)
        {
            if (number % 10 == 3)
                a3++;
            else if (number % 10 == 5)
                a5++;
            else if (number % 10 == 7)
                a7++;
            else
            {
                is357 = false;
                break;
            }
            number /= 10;
        }
        if (is357 && a3 && a5 && a7)
        {
            ans++;
        }
    }
    cout << ans << endl;
}