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 mother bear and her two young are crossing a shallow river'. How many words start with the letter 'a' in the sentence.

Ex Output:
4


Ex Input:
Sentence: 'a couple of giraffes that are walking around'. How many words start with the letter 'c' in the sentence.

Ex Output:
1


Ex Input:
Sentence: 'a woman wearing a mask is holding up a stuffed bear'. How many words start with the letter 'a' in the sentence.

Ex Output:

3