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

Input: Consider Input: Sentence: 'a snow filled mountain with a guy with ski's'. Find frequency of the letter 'f'

Output: 1

Input: Consider Input: Sentence: 'a man on a skateboard going down a ramp while people are watching'. Find frequency of the letter 'w'

Output: 3

Input: Consider Input: Sentence: 'a man wearing a tie leaning against a tree'. Find frequency of the letter 'e'
Output: 5