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

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 herd of giraffe walking across a field'. Find frequency of the letter 'k'

Ex Output:
1


Ex Input:
Sentence: 'people sitting down at a table with chocolate covered donuts'. Find frequency of the letter 'e'

Ex Output:

6