N, M = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

R = [0 for _ in range(M)]
for i in range(N):
    R[A[i]-1] += 1
ANS = 0
for i in range(M):
    if B[i]<R[i]:
       ANS += R[i] - B[i]
print(ANS)