Valid Identifier Checker

You are given a string. Your task is to determine whether the string is a valid identifier.

A string is considered a valid identifier if it meets the following conditions:

• The string is non-empty.
• The first character is either a letter (a-z or A-Z) or an underscore ('_').
• Every character in the string is either a letter, a digit (0-9), or an underscore.

For example:

• variable_name_1 is valid.
• _startWithUnderscore is valid.
• 1_startWithNumber is not valid because it starts with a digit.
• variable-name is not valid because of the hyphen.

Your program should read the input from standard input and output either True or False to standard output.

inputFormat

The input consists of a single line containing a non-empty string which may include letters, digits, underscores, or other characters.

Note: The string may be empty, in which case it should be considered invalid.

outputFormat

Output a single line: True if the input string is a valid identifier according to the rules given above, otherwise output False.

## sample

variable_name_1

True