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.

Example Input: Sentence: 'a train passes over a quiet city park on a bridge'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a kitchen filled with appliances and cooking utensils'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a couple of men giving a fist bump as one holds a surfboard'. How many words start with the letter 'f' in the sentence.
Example Output:
1