Is It a Valid Identifier?

Read one line of text and decide whether it is a valid Java identifier.

A valid identifier: is non-empty; starts with a letter, _ or $; every character is a letter, digit, _ or $; and is not a Java reserved word (also excluding true, false, null).

Input: one line — the candidate (it may contain spaces, which make it invalid).

Output: Valid or Invalid.

Example 1

Input

totalMarks

Output

Valid

Example 2

Input

2name

Output

Invalid

1 <= line length <= 60

Hint 1

Check the first character, then every remaining character, against the rules.

Hint 2

Character.isLetter, Character.isLetterOrDigit, and a check for '_' / '$' cover the cases.

Hint 3

Finally, reject the word if RESERVED contains it.

First rule out the empty string and reserved words. Then verify the first character is a letter, underscore or dollar sign, and that every other character is a letter, digit, underscore or dollar sign. A space fails that test, so "my age" is Invalid.