Hermoine loves data

Hermoine started showing intersest in data analyzing too apart from wizardary. But, she is very new to the field. She was challenged by her friend Ron to do a simple task. A chat history was given which contains $N$ words and she has to find the most used word in the chat. She doesn’t want to lose this challenge. So, she seeks your help. Help her find the most recurring word, $S$ in the chat histo