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

Input: Consider Input: Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'

Output: 3


Input: Consider Input: Sentence: 'three birds are sitting on a tree in a forest'. Find frequency of the letter 'h'

Output: 1


Input: Consider Input: Sentence: 'an elephant walks around a tree in a field'. Find frequency of the letter 'd'


Output: 2