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

Input: Consider Input: Sentence: 'two people and two children walking in a building'. Find frequency of the letter 'd'

Output: 3


Input: Consider Input: Sentence: 'an airplane is being towed away from the jet bridge'. Find frequency of the letter 's'

Output: 1


Input: Consider Input: Sentence: 'a woman on a tennis court in the sun'. Find frequency of the letter 't'


Output: 3