from typing import List
def remove_duplicates(numbers: List[int]) -> List[int]:
    import collections
    c = collections.Counter(numbers)
    return [n for n in numbers if c[n] <= 1]
from typing import List
def mean_absolute_deviation(numbers: List[float]) -> float:
    mean = sum(numbers) / len(numbers)
    return sum(abs(x - mean) for x in numbers) / len(numbers)