Word Frequency Counter

Given a string of words, possibly containing punctuation and varying cases, your task is to count the frequency of each unique word (case-insensitive) and output the results in a JSON format. A word is defined as a sequence of alphanumeric characters.

For example, for the input Hello, world!, the correct output is {"hello": 1, "world": 1}.

inputFormat

The input is provided via stdin as a single string. The string may contain spaces, punctuation, or even multiple lines.

outputFormat

The output should be the frequency dictionary in a JSON format printed to stdout. The keys (words) must be in lower case, punctuation should be ignored, and the keys should be sorted in alphabetical order.

Hello world

{"hello": 1, "world": 1}