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

Input: Consider Input: Sentence: 'a river with a long dragon boat in it and rowers on the boat in sets of two, along with two other people'. Find frequency of the letter 'h'

Output: 4


Input: Consider Input: Sentence: 'two persons standing outside a moving sub train'. Find frequency of the letter 'a'

Output: 3


Input: Consider Input: Sentence: 'a t.v. that is sitting on a wooden t.v. stand'. Find frequency of the letter 's'


Output: 3