Valid Filename Checker

You are given a filename and need to determine whether it is a valid filename based on the following rules:

• The filename must start with one or more lowercase letters [a-z]+.
• This must be optionally followed by a series of digits [0-9]*.
• The filename must end with the literal string .txt.

In mathematical terms, a valid filename f satisfies:

$$f \in \{ s \mid s \, \text{matches} \, ^[a-z]+[0-9]*\.txt$ \} $$

Your task is to read the input filename from standard input and print "Valid" if the filename meets the above conditions, or "Invalid" otherwise.

inputFormat

The input consists of a single line containing a string, which represents the filename to be validated. There are no extra spaces or additional input lines.

outputFormat

Output a single line. Print "Valid" if the filename meets the specified format; otherwise, print "Invalid".

## sample

notes123.txt

Valid