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

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

Ex Output:
3


Ex Input:
Sentence: 'a person with some scissors over a bowl'. Find frequency of the letter 's'

Ex Output:
6


Ex Input:
Sentence: 'two police motorcycles lead a motorcade or parade'. Find frequency of the letter 'c'

Ex Output:

4