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

Ex Input:
Sentence: 'a blue fire hydrant painted on the bottom of it'. Find frequency of the letter 'h'

Ex Output:
2


Ex Input:
Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'

Ex Output:
1


Ex Input:
Sentence: 'a little boy sitting on a bed in a bedroom'. Find frequency of the letter 'e'

Ex Output:

3