A toll gate reads an amount as a raw text token and must accept it only if it is a strictly-formatted integer. The token (which contains no spaces) is a valid amount if and only if all of the following hold:
- It consists of an optional leading minus sign
-followed by one or more decimal digits. - A leading plus sign is never allowed.
- There are no leading zeros: the digit portion is either the single digit
0, or a nonzero digit followed by any digits. - The token
-0(negative zero) is not allowed. - Its integer value lies within the inclusive range
-1000000000to1000000000.
If the token is a valid amount, print its integer value. Otherwise print INVALID.
Input format
Line 1: the token to validate (a non-empty string with no spaces).
Output format
A single line: the integer value of the token if it is valid, otherwise the word INVALID.
Constraints
- 1 <= length of the token <= 20
- The token contains no whitespace.