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

Input: Consider Input: Sentence: 'a woman is taking a sip of a drink from a glass'. Find frequency of the letter 'i'

Output: 4


Input: Consider Input: Sentence: 'a herd of giraffes in tall african grass'. Find frequency of the letter 'a'

Output: 6


Input: Consider Input: Sentence: 'a picture of of martin luther king jr. standing in front of the lincoln memorial'. Find frequency of the letter 'f'


Output: 4