Count Valid Passwords

You are given an integer m representing the length of a password. A valid password satisfies the following conditions:

• It is composed only of lowercase English letters.
• No two adjacent characters are the same.

The total number of valid passwords of length m is given by the formula:

$$26 \times 25^{m-1}$$

where the first character can be chosen in 26 ways and each subsequent character in 25 ways (all letters except the one immediately preceding it).

inputFormat

The input consists of a single integer m (1 \leq m \leq 20) given on a single line.

outputFormat

Output a single number which is the total count of valid passwords of length m according to the given rules.

## sample

1

26