## https://yukicoder.me/problems/no/1922


def main():
    N = int(input())
    P = list(map(int, input().split()))
    Q = list(map(int, input().split()))

    q_map = {}
    for i, q in enumerate(Q):
        q_map[q] = i

    p_array = [0] * N
    for i in range(N):
        j = q_map[P[i]]
        p_array[i] = j

    p_array2 = [(i, p) for i, p in enumerate(p_array)]
    p_array2.sort(key=lambda x : x[1])
    array_list = []
    for i, _ in p_array2:
        if len(array_list) == 0:
            array_list.append(i)
        else:
            if array_list[-1] > i:
                array_list.append(i)
            else:
                array_list[-1] = i
    
    count = 0
    ar_num = len(array_list)
    while ar_num > 1:
        ar_num = (ar_num + 1) // 2
        count += 1
    print(count)







if __name__ == "__main__":
    main()