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: 'man is snow gear and skis skiing in the snow'. Find frequency of the letter 'i'

Output: 5


Input: Consider Input: Sentence: 'a group of people releasing balloons in a field'. Find frequency of the letter 'n'


Output: 3