Valid Digital Lock System

You are given a string representing a digital lock system. The string consists of characters '#' and '.'. The system is considered valid if it does not contain two consecutive period characters.

In other words, a string s is valid if and only if there does not exist an index \(i\) such that \(s_i = '.'\) and \(s_{i+1} = '.'\). For example, the string "##.#.#.#" is valid, whereas "##..##" is invalid.

Note that an empty string is also considered valid.

inputFormat

The input is provided via standard input (stdin) as a single line containing the lock system string, which may consist of characters '#' and '.'.

outputFormat

The output should be printed to standard output (stdout) as a single line containing either True if the lock system is valid, or False otherwise.

##.#.#.#

True