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 crowd of people on the street one of which is taking pictures with a cell phone'. How many words start with the letter 'o' in the sentence.
Example Output: 4

Example Input: Sentence: 'a fighter jet on a runway with a cover over the cockpit'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a tennis match in progress in a stadium'. How many words start with the letter 'm' in the sentence.
Example Output:
1