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: 'some nice decorations left on a window pane'. How many words start with the letter 'l' in the sentence.
Example Output: 1

Example Input: Sentence: 'a close up of a baby with a tooth brush'. How many words start with the letter 'a' in the sentence.
Example Output: 3

Example Input: Sentence: 'a horse grazes on some green grass'. How many words start with the letter 'g' in the sentence.
Example Output:
3