### Problem Statement

John thinks 4 and 7 are lucky digits, and all other digits are not lucky. A lucky number is a number that contains only lucky digits in decimal notation.

You are given an int n. Return the largest lucky number that is less than or equal to n.

### Definition

 Class: TheLargestLuckyNumber Method: find Parameters: int Returns: int Method signature: int find(int n) (be sure your method is public)

### Constraints

-n will be between 4 and 1,000,000, inclusive.

### Examples

0)

 `100`
`Returns: 77`
 77 is the largest lucky number that is not greater than 100.
1)

 `75`
`Returns: 74`
 74 is the lucky number that immediately precedes 77.
2)

 `5`
`Returns: 4`
 The smallest lucky number is 4.
3)

 `474747`
`Returns: 474747`
 n is a lucky number.

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=8567

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=12175&pm=8567

Vasyl[alphacom]

#### Testers:

PabloGilberto , Olexiy , marek.cygan , ivan_metelsky

Simulation