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

Input: Consider Input: Sentence: 'a long row of tables displaying lots of fruit'. Find frequency of the letter 'o'

Output: 5

Input: Consider Input: Sentence: 'an old glass vase containing flowers on a glass table'. Find frequency of the letter 'b'

Output: 1

Input: Consider Input: Sentence: 'the kitchen area is clean and ready to use'. Find frequency of the letter 't'
Output: 3