A = [-15, -9, -6, -3, 1, 3, 6, 20]
nums = []
while len(A) > 0:
firstNum = max(abs(A[-1]), abs(A[0]))
if not firstNum in nums:
nums.append(firstNum)
if -firstNum in A:
A.remove(-firstNum)
else:
A.remove(firstNum)
else:
if -firstNum in A:
A.remove(-firstNum)
else:
A.remove(firstNum)
nums.reverse()
print(nums)
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