def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    P = list(map(int, input[ptr:ptr+N]))
    ptr += N
    Q = list(map(int, input[ptr:ptr+N]))
    ptr += N

    pos_in_P = {num: i for i, num in enumerate(P)}

    blocks = 1
    current_min = pos_in_P[Q[0]]
    for i in range(1, N):
        num = Q[i]
        pos = pos_in_P[num]
        if pos < current_min:
            blocks += 1
            current_min = pos

    print(blocks - 1)

if __name__ == "__main__":
    main()