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# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
class Program
{
	static void Main(string[] args)
	{
		// 整数の入力
		int a = int.Parse(Console.ReadLine());
		string nagomi;
		int b=0;
        int na=0;
		int go=0;
		int mi=0;
		int hoka=0;
		int answer=0;
		for(int i=0;i<a+1;i++){
			b=i;
			while(b!=0){
				if(b%10==7){
					na++;
				}
				else if(b%10==5){
					go++;
				}
				else if(b%10==3){
					mi++;
				}
				else{
					hoka++;
					break;
				}
				b=b/10;
			}
			if(na>0 && go>0 && mi>0 && hoka==0){
				answer++;
			}
			na=0;
			go=0;
			mi=0;
			hoka=0;
		}
		//出力
		Console.WriteLine(answer);
	}
}