Count Unique Words

You are given a single line of text containing a series of words separated by spaces. Your task is to count the number of unique words in the input after converting all letters to lowercase. This means that words such as "Hello", "hello", and "HELLO" are considered the same word.

Example: For the input "Hello world hello", there are 2 unique words: "hello" and "world".

Be sure to handle inputs with different cases and extra spaces correctly.

inputFormat

The input is provided via standard input (stdin) and consists of a single line containing one or more words separated by spaces. Words may contain uppercase and lowercase English letters.

outputFormat

The output should be printed to standard output (stdout) and consist of a single integer: the number of unique words in the input string.

## sample

hello

1

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