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

Ex Input:
Sentence: 'a couple of items that are on the wall'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'there is a stop sign that has a reflection in a puddle'. Find frequency of the letter 'e'

Ex Output:
5


Ex Input:
Sentence: 'the giraffe is drinking water from a pond'. Find frequency of the letter 'o'

Ex Output:

2