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

Input: Consider Input: Sentence: 'a dog has found a rather large stick for playing fetch'. Find frequency of the letter 't'

Output: 3

Input: Consider Input: Sentence: 'an commercial airline airplane flies above the clouds'. Find frequency of the letter 'n'

Output: 3

Input: Consider Input: Sentence: 'a couple of young people standing in front of a tv'. Find frequency of the letter 'i'
Output: 2