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 cars and house on truck passing in a street'. Find frequency of the letter 'i'

Output: 2


Input: Consider Input: Sentence: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'a skateboarder getting ready to do a trick on his board'. Find frequency of the letter 'd'


Output: 4