import sys
# input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n, m = na()
a = na()
b = na()
ans = 0
for i in range(n):
    a[i] -= 1
    if b[a[i]] == 0:
        ans += 1
    else:
        b[a[i]] -= 1

print(ans)