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: 'three groups of yellow flowers in vases on table'. How many words start with the letter 't' in the sentence.
Example Output: 2

Example Input: Sentence: 'many colorful umbrellas hang over a colorful street'. How many words start with the letter 'm' in the sentence.
Example Output: 1

Example Input: Sentence: 'a pizza with cheese tomatoes and other toppings on baking board'. How many words start with the letter 'o' in the sentence.
Example Output:
2