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

[EX Q]: Sentence: 'a herd of giraffes in tall african grass'. Find frequency of the letter 'a'
[EX A]: 6

[EX Q]: Sentence: 'a castle like bed room that has the era of templar knight similarities'. Find frequency of the letter 'm'
[EX A]: 3

[EX Q]: Sentence: 'a white train on the tracks next to a passenger platform'. Find frequency of the letter 'k'
[EX A]:
1