N, Q = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
INF = 10 ** 6
dp = [0] + [INF] * (N - 1)
for b in B:
    dp1 = [INF] * N
    dp2 = [INF] * N
    for i in range(N):
        j = N - i - 1
        if i == 0:
            dp1[i] = dp[i]
            dp2[j] = dp[j]
        else:
            dp1[i] = min(dp[i], dp1[i - 1] + 1)
            dp2[j] = min(dp[j], dp2[j + 1] + 1)
    dp = [INF] * N
    for i in range(N):
        if A[i] == b:
            dp[i] = min(dp1[i], dp2[i])

print(min(dp))