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

Ex Input:
Sentence: 'an old boat on a beach near a large body of water'. Find frequency of the letter 'a'

Ex Output:
8

Ex Input:
Sentence: 'red chair next to side table with lamp in residential home'. Find frequency of the letter 'm'

Ex Output:
2

Ex Input:
Sentence: 'a snowboarder with tan pants going down a small hill'. Find frequency of the letter 'i'

Ex Output:
3