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: 'three friends sit and talk while waiting for the train'. How many words start with the letter 'a' in the sentence.

Ex Output:
1


Ex Input:
Sentence: 'birds are standing in a row on a wooden railing'. How many words start with the letter 'a' in the sentence.

Ex Output:
3


Ex Input:
Sentence: 'two men with a wine glass in their hand at a table'. How many words start with the letter 'a' in the sentence.

Ex Output:

3