Given an array of integers of length n, a1,a2,...,an.
Now you need to classify each element of the array.
Each element is either classified into class a, class b, or class c.
Let the sum of all the elements of class a be suma, the sum of all the elements of class b be sumb, and the sum of all the elements of class c be sumc.
Calculate the maximum possible value of suma -sumb-sumc.
If the number of elements of a class is 0, then the sum of the elements of that class is considered to be 0.