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 in a black shirt prepares to catch a frisbee'. Find frequency of the letter 'f'

Output: 1


Input: Consider Input: Sentence: 'a passenger train that is going over a bridge'. Find frequency of the letter 't'

Output: 3


Input: Consider Input: Sentence: 'a man pulling a wagon through a field with cars in the background'. Find frequency of the letter 'u'


Output: 3