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

Input: Consider Input: Sentence: 'a blue tripocal bird is perched on a wooden fence'. Find frequency of the letter 'd'

Output: 3


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 stop sign outside of the local supercenter'. Find frequency of the letter 'e'


Output: 5