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

Input: Consider Input: Sentence: 'two metal  benches on an empty train platform'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'a grapefruit, toast, coffee and other items are on a tray'. Find frequency of the letter 't'

Output: 6


Input: Consider Input: Sentence: 'a bird on a vine in the rain forest'. Find frequency of the letter 'f'


Output: 1