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 bird sitting on the neck of a giraffe'. How many words start with the letter 'o' in the sentence.
Example Output: 2

Example Input: Sentence: 'a kitchen with hard wood floors and metallic appliances'. How many words start with the letter 'm' in the sentence.
Example Output: 1

Example Input: Sentence: 'a girl celebrates her dogs first birthday with cake'. How many words start with the letter 'a' in the sentence.
Example Output:
1