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 stop sign and a no stopping sign are on a street corner'. How many words start with the letter 's' in the sentence.

Ex Output:
5


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 fat hot dog on a bun next to some mustard'. How many words start with the letter 'a' in the sentence.

Ex Output:

2