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

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

Ex Output:
2


Ex Input:
Sentence: 'a crowd of people skiing and enjoying the snow'. Find frequency of the letter 'o'

Ex Output:
5


Ex Input:
Sentence: 'a line of buses in a parking lot with people standing around'. Find frequency of the letter 'o'

Ex Output:

4