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

[Q]: Sentence: 'two metal  benches on an empty train platform'. Find frequency of the letter 'n'
[A]: 4


[Q]: Sentence: 'a downhill skier with snow plumes behind them'. Find frequency of the letter 'i'
[A]: 4


[Q]: Sentence: 'a guy is in a ugly gruesome blood covered costume'. Find frequency of the letter 'u'
[A]:
4