Mrs. Toad has a class of $2017$ students, with unhappiness levels $1, 2, \ldots, 2017$ respectively. Today in class, there is a group project and Mrs. Toad wants to split the class into exactly $15$ groups. The unhappiness level of a group is the average unhappiness of its members, and the unhappiness of the class is the sum of the unhappiness of all $15$ groups. What's the minimum unhappiness of the class Mrs. Toad can achieve by splitting the class into $15$ groups?

Let's think step by step and output the final answer within \boxed{}.
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