In this task, you need to count the number of words in a sentence that start with the given letter. Answer with numbers and not words.

Ex Input:
Sentence: 'a guy a skateboard jumping in the air'. How many words start with the letter 'a' in the sentence.

Ex Output:
3


Ex Input:
Sentence: 'several people are playing frisbee in a park'. How many words start with the letter 'a' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a bus at a stop waiting on passengers to board'. How many words start with the letter 'a' in the sentence.

Ex Output:

3