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

Ex Input:
Sentence: 'a bunch of people are standing out in a field a red one has their arms out as a white ball is in the air'. Find frequency of the letter 'e'

Ex Output:
9


Ex Input:
Sentence: 'a woman is taking a sip of a drink from a glass'. Find frequency of the letter 'i'

Ex Output:
4


Ex Input:
Sentence: 'a woman sits beside the wreck of a car and motorcycle'. Find frequency of the letter 'k'

Ex Output:

1