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

Input: Consider Input: Sentence: 'a person on a sidewalk jumping with an umbrella'. Find frequency of the letter 'a'

Output: 5


Input: Consider Input: Sentence: 'two elephants facing each other touching trunks in an enclosure'. Find frequency of the letter 'f'

Output: 1


Input: Consider Input: Sentence: 'a dog on a leash near a bowl of water'. Find frequency of the letter 'r'


Output: 2