In this task, you need to count the number of times the given letter appears in the given sentence.

Input: Consider Input: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'r'

Output: 3


Input: Consider Input: Sentence: 'a white paper plate with a slice of pizza on it'. Find frequency of the letter 'h'

Output: 2


Input: Consider Input: Sentence: 'a boy learning to skateboard in a park'. Find frequency of the letter 'a'


Output: 6