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 zeppelin flying in the air as a water spouts occurs in a city lake'. How many words start with the letter 'a' in the sentence.

Ex Output:
5


Ex Input:
Sentence: 'a group of young people riding snow boards down a snow covered hillside'. How many words start with the letter 'a' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a small elephant is standing alone in the enclosure'. How many words start with the letter 's' in the sentence.

Ex Output:

2