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

Ex Input:
Sentence: 'tow birds flying by a long necked crane'. Find frequency of the letter 'f'

Ex Output:
1

Ex Input:
Sentence: 'a castle like bed room that has the era of templar knight similarities'. Find frequency of the letter 'm'

Ex Output:
3

Ex Input:
Sentence: 'a person taking a photo of a cat on a car'. Find frequency of the letter 'o'

Ex Output:
5