' 1269번 대칭 차집합 '
https://www.acmicpc.net/problem/1269
union = list(set(lst1) | set(lst2))
union = list(set().union(lst1,lst2))
intersection = list(set(lst1) & set(lst2))
intersection = list(set(lst1).intersection(lst2))
complement = list(set(lst1) - set(lst2))
complement = list(set(lst1).difference(lst2))
sym_diff = list(set(lst1) ^ set(lst2))
sym_diff = list(set(lst1).symmetric_difference(lst2))
A, B = map(int,input().split())
lsta = list(map(int,input().split()))
lstb = list(map(int,input().split()))
l = list(set(lsta)^set(lstb))
print(len(l))