Deleting a lucky string

Limits: 2 sec., 256 MiB

This statement was translated automatically from Ukrainian.

Today everyone is celebrating Lucky Numbers Day!

One of the traditional activities done on this day is checking various properties of lucky numbers.

You are given a string representing a lucky number \(s\) – it has an odd length and consists only of the characters 4 and 7. In one step, you can choose two identical characters of the string that are not adjacent and delete them. The task is to determine whether it is possible to obtain a string of length 1 as a result of performing an unlimited number of such operations.

Can you handle this task?

Input

The single line contains the string \(s\) – the proposed lucky number.

Output

In a single line, print YES if it is possible to obtain a string of length 1. Otherwise, print NO.

Constraints

\(1 \le |s| \le 10^5\),

\(s_i \in \{4, 7\}\),

\(s\) has an odd length.

Samples

Input (stdin) сopy	Output (stdout) сopy
7447744	YES

Input (stdin) сopy	Output (stdout) сopy
44777	NO

Notes

In the first example, you can obtain a string of length 1 by performing, for example, the following operations:

1. Delete the first and fourth characters: 44744

2. Delete the first and last characters: 474

3. Delete the first and last characters: 7