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 and a child walking down a street with a kite'. Find frequency of the letter 'n'

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: 'an old truck on a street in front of warehouse'. Find frequency of the letter 't'


Output: 4