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 close up of three older men standing near one another'. How many words start with the letter 'a' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a couple of people are riding horses in a village'. How many words start with the letter 'a' in the sentence.

Ex Output:
3


Ex Input:
Sentence: 'a person taking a picture of a mountain valley'. How many words start with the letter 'a' in the sentence.

Ex Output:

3