n, Q = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
inf = 1 << 60
dp = [inf] * n
dp[0] = 0

for b in B:
    ndp = [inf] * n
    mi = inf
    for i in range(n):
        a = A[i]
        mi = min(mi + 1, dp[i])
        if a == b:
            ndp[i] = min(ndp[i], mi)
    mi = inf
    for i in range(n - 1, -1, -1):
        a = A[i]
        mi = min(mi + 1, dp[i])
        if a == b:
            ndp[i] = min(ndp[i], mi)
    dp = ndp

print(min(dp))