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: 'there is a lap top on a desk at a office'. How many words start with the letter 'o' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a small airplane sitting on top of a runway'. How many words start with the letter 'a' in the sentence.

Ex Output:
3


Ex Input:
Sentence: 'a school bus going by a sidewalk and trees with bushes'. How many words start with the letter 's' in the sentence.

Ex Output:

2