Largest lucky number

Limits: 1 sec., 256 MiB

This statement was translated automatically from Ukrainian.

It is well known that a lucky number is a positive integer whose decimal representation contains only fours and sevens. For example, 4, 7, 47, 7777, and 4744474 are lucky numbers.

You are given a lucky number \(n\). What is the largest lucky number that can be obtained by changing exactly one digit in the number \(n\)?

Input

The single line contains a single lucky number \(n\).

Output

Output the largest number that can be obtained by replacing exactly one digit in the given number.

Constraints

\(1 \le n \le 10^9\),

\(n\) is lucky.

Samples