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

Ex Input:
Sentence: 'a group of cows that are standing in the grass'. Find frequency of the letter 'g'

Ex Output:
3


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: 'small giraffe sitting on the ground while the sun hits its body'. Find frequency of the letter 'h'

Ex Output:

4