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

Input: Consider Input: Sentence: 'the two dogs are playing in the pen together'. Find frequency of the letter 'o'

Output: 3

Input: Consider Input: Sentence: 'vanity sitting atop a base with two doors and a mirror overhead'. Find frequency of the letter 'n'

Output: 3

Input: Consider Input: Sentence: 'bunch of dumbass zebras roaming the prairie and shitting'. Find frequency of the letter 't'
Output: 3