input: Write a python function to compute the total of unique elements in an array.
  assert find_unique_sum([1,2,3,1,1,4,5,6],8) == 21
  assert find_unique_sum([1,10,9,4,2,10,10,45,4],9) == 71
  assert find_unique_sum([12,10,9,45,2,10,10,45,10],9) == 78
output: def find_unique_sum(arr, n):
      return sum(set(arr))