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 closeup picture of a polar bears head'. How many words start with the letter 'a' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a photo of a waterway with several boats along the shore'. How many words start with the letter 'w' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'an older man and woman riding on a motorcycle'. How many words start with the letter 'a' in the sentence.

Ex Output:

3