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

Input: Consider Input: Sentence: 'a golden haired dog looking out of an open window'. Find frequency of the letter 'd'

Output: 4


Input: Consider Input: Sentence: 'a group of three dogs laying on a kitchen floor'. Find frequency of the letter 'r'

Output: 3


Input: Consider Input: Sentence: 'a trio of women walking with two holding umbrella's'. Find frequency of the letter 'm'


Output: 2