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 bus stops in order to pick up passengers'. How many words start with the letter 'p' in the sentence.

Ex Output:
2


Ex Input:
Sentence: 'a boat floating on a lake next to a shore filled with buildings'. How many words start with the letter 'n' in the sentence.

Ex Output:
1


Ex Input:
Sentence: 'a surfer riding a wave in the surf'. How many words start with the letter 'a' in the sentence.

Ex Output:

2