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

Input: Consider Input: Sentence: 'a person does a trick on a ramp on a snowboard'. Find frequency of the letter 's'

Output: 3


Input: Consider Input: Sentence: 'a photo of a toilet which is not clean'. Find frequency of the letter 'w'

Output: 1


Input: Consider Input: Sentence: 'three firefighters on and around a fire truck spraying water'. Find frequency of the letter 't'


Output: 4