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

Input: Consider Input: Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'

Output: 2

Input: Consider Input: Sentence: 'the man is holding a plastic sled with snow in it next to a child'. Find frequency of the letter 'g'

Output: 1

Input: Consider Input: Sentence: 'an open umbrella near a stair way with a sky background'. Find frequency of the letter 'e'
Output: 3