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

Input: Consider Input: Sentence: 'tow birds flying by a long necked crane'. Find frequency of the letter 'f'

Output: 1


Input: Consider Input: Sentence: 'a dog is shown sitting on rocks by the beach'. Find frequency of the letter 'a'

Output: 2


Input: Consider Input: Sentence: 'a man with an older flip-phone is taking his picture'. Find frequency of the letter 'a'


Output: 4