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

Ex Input:
Sentence: 'a display case filled with lots of different clocks'. Find frequency of the letter 'w'

Ex Output:
1


Ex Input:
Sentence: 'a white bowl filled with peeled orange slices'. Find frequency of the letter 's'

Ex Output:
2


Ex Input:
Sentence: 'woman sitting with her dog, and other women are around'. Find frequency of the letter 'w'

Ex Output:

3