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

Ex Input:
Sentence: 'a bus is stopped in front of a graphic statue'. Find frequency of the letter 'e'

Ex Output:
2


Ex Input:
Sentence: 'a gray colored pigeon that is perched on a railing outside of a building, with other buildings in the background'. Find frequency of the letter 'e'

Ex Output:
7


Ex Input:
Sentence: 'a plate with cakes on it above some young people'. Find frequency of the letter 't'

Ex Output:

3