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>
#pragma GCC optimize("Ofast")
using namespace std;
string S; 
int N;
int Ans=0;
int Cnt3=1,Cnt5=1,Cnt7=1;
int bit=1;
string T="357";
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	cin>>S;
	N=atoi(S.c_str());
	int Len=S.length();
	for(int i=0;i<Len-3;i++) T='0'+T;
	while(atoi(T.c_str())<=N)
	{
		if(!Cnt3||!Cnt5||!Cnt7){}
		else ++Ans;
		char ch=T[Len-1];
		if(ch=='0')
		{
			++Cnt3;
			T[Len-1]='3';
		}
		else if(ch=='3')
		{
			--Cnt3,++Cnt5;
			T[Len-1]='5'; 
		}
		else if(ch=='5')
		{
			--Cnt5,++Cnt7;
			T[Len-1]='7'; 
		}
		else
		{
			bit=1;
			while(T[Len-bit]=='7')
			{
				--Cnt7,++Cnt3;
				T[Len-bit]='3';
				++bit;
			}
			ch=T[Len-bit];
			if(ch=='0')
			{
				++Cnt3;
				T[Len-bit]='3';
			}
			else if(ch=='3')
			{
				--Cnt3,++Cnt5;
				T[Len-bit]='5'; 
			}
			else if(ch=='5')
			{
				--Cnt5,++Cnt7;
				T[Len-bit]='7'; 
			}
		}
	}
	cout<<Ans<<endl;
	return 0;
}