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

Input: Consider Input: Sentence: 'cars parked outside if a retail store'. Find frequency of the letter 'd'

Output: 2


Input: Consider Input: Sentence: 'a stop sign near a rail road crossing sign'. Find frequency of the letter 'g'

Output: 3


Input: Consider Input: Sentence: 'a group of zebras all pile around a bunch of grass'. Find frequency of the letter 'a'


Output: 6