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 man hits a tennis ball with a racket on the court'. Find frequency of the letter 'c'

Output: 2


Input: Consider Input: Sentence: 'a cheesy pizza sitting on top of a white plate'. Find frequency of the letter 'e'


Output: 4