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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
class Program{
	static void Main(){
		string s=Console.ReadLine();
		int n=s.Length,ans=0;
		int[,,,] dp=new int[n+1,2,2,8];
		dp[0,0,0,0]=1;
		for(int i=0;i<n;i++){
			for(int j=0;j<2;j++){
				for(int k=0;k<2;k++){
					for(int l=0;l<8;l++){
						int lm=j==0?Math.Min(s[i]-'0',8):7;
						for(int d=k*3;d<=lm;d=(d|1)+2){
							int q=0;
							if((l&1)==1||d==3){q|=1;}
							if((l&2)==2||d==5){q|=2;}
							if((l&4)==4||d==7){q|=4;}
							dp[i+1,(j==1||d<lm)?1:0,(k==1||d!=0)?1:0,q]+=dp[i,j,k,l];
						}
					}
				}
			}
		}
		for(int j=0;j<2;j++){ans+=dp[n,j,1,7];}
		Console.WriteLine("{0}",ans);
	}
}