N = int(input())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
invQ = [0] * N
invP = [0] * N
for i in range(N):
    P[i] -= 1
    Q[i] -= 1
    invQ[Q[i]] = i
for i in range(N):
    invP[invQ[P[i]]] = i
g = 1
for i in range(N - 1):
    if invP[i] > invP[i + 1]:
        g += 1
ans = 0
while g > 1:
    ans += 1
    g = (g + 1) >> 1
print(ans)