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

Input: Consider Input: Sentence: 'a gray elephant is in a grassy field'. Find frequency of the letter 'e'

Output: 3


Input: Consider Input: Sentence: 'two young ladies that are dancing in the room together'. Find frequency of the letter 'a'

Output: 4


Input: Consider Input: Sentence: 'an airplane flying against a clear blue sky'. Find frequency of the letter 'l'


Output: 4