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

Ex Input:
Sentence: 'a bird is perched on a container in a person's hand'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'a traffic signal by a wire filled with some birds'. Find frequency of the letter 'e'

Ex Output:
3


Ex Input:
Sentence: 'two men standing while playing a video game'. Find frequency of the letter 'e'

Ex Output:

4