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

Ex Input:
Sentence: 'people plating cake in an office meeting room'. Find frequency of the letter 'g'

Ex Output:
2


Ex Input:
Sentence: 'a large grass pasture land with sheep grazing on grass'. Find frequency of the letter 'a'

Ex Output:
7


Ex Input:
Sentence: 'man and woman cutting a white wedding cake'. Find frequency of the letter 'n'

Ex Output:

5