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: 'there is a lap top on a desk at a office'. How many words start with the letter 'o' in the sentence.
Example Output: 2

Example Input: Sentence: 'a street sign view in a very blurry picture'. How many words start with the letter 's' in the sentence.
Example Output: 2

Example Input: Sentence: 'european city with older stone structures and busy street'. How many words start with the letter 's' in the sentence.
Example Output:
3