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

Ex Input:
Sentence: 'a dilapidated bench in a park under a tree'. Find frequency of the letter 'p'

Ex Output:
2


Ex Input:
Sentence: 'a police officer who is riding on a horse'. Find frequency of the letter 'p'

Ex Output:
1


Ex Input:
Sentence: 'the man is standing beside of the giraffe'. Find frequency of the letter 'i'

Ex Output:

4