from collections import deque
N, Q = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
G = [[] for _ in range(N * Q + N + 1)]
for j in range(Q):
    for i in range(N):
        if i == N - 1: continue
        G[j * N + i].append((j * N + i + 1, 1))
        G[j * N + i + 1].append((j * N + i, 1))
    for i in range(N):
        if A[i] != B[j]: continue
        if j != Q - 1: G[j * N + i].append(((j + 1) * N + i, 0))
        else: G[j * N + i].append((N * Q, 0))
dist = [10 ** 9 + 1] * (N * Q + 1)
D = deque([0])
dist[0] = 0
while len(D) > 0:
    v = D.popleft()
    for nv, c in G[v]:
        d = dist[v] + c
        if d < dist[nv]:
            dist[nv] = d
            if c: D.append(nv)
            else: D.appendleft(nv)
print(dist[N * Q])