def closestNumbers(arr):
    # Sort the array
    arr = sorted(arr)

    # Create a dictionary to store absolute differences
    difference_dict = {}
    for i in range(len(arr) - 1):
        difference = abs(arr[i] - arr[i + 1])
        # Store pairs for each unique difference
        if difference not in difference_dict:
            difference_dict[difference] = []
        difference_dict[difference].append((arr[i], arr[i + 1]))  # Store as tuples

    # Find the minimum absolute difference
    min_difference = min(difference_dict.keys())

    # Get the pairs corresponding to the minimum difference
    closest_pairs = difference_dict[min_difference]

    # Flatten the closest pairs into a list
    result = [num for pair in closest_pairs for num in pair]

    return list(set(result))