def make_anagram_1(a, b):
    """Using a dictionary: O(n_a+n_b) time""" 
    count_dict = {}
    for n in a:
        if n in count_dict.keys():
            count_dict[n] +=1
        else:
            count_dict[n] = 1
    for n in b:
        if n in count_dict.keys():
            count_dict[n] -=1
        else:
            count_dict[n] = -1
    return sum(map(abs, count_dict.values()))