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 group of dogs standing next to each other while on leashes'. How many words start with the letter 'o' in the sentence.

Ex Output:
3


Ex Input:
Sentence: 'several white boats are anchored at a marina'. How many words start with the letter 's' in the sentence.

Ex Output:
1


Ex Input:
Sentence: 'a large boat going down a channel by some grass and big buildings in the background'. How many words start with the letter 'b' in the sentence.

Ex Output:

5