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

    most_far_destination = 2
    destination_reverse_dict = {}
    for idx, r in enumerate(R, 1):
        if r < most_far_destination:
            continue
        destination_reverse_dict.update(
            {dest: idx for dest in range(most_far_destination, r + 1)}
        )
        most_far_destination = r + 1

    destination = N
    ctr = 0
    while destination != 1:
        destination = destination_reverse_dict[destination]
        ctr += 1

    print(ctr)


if __name__ == "__main__":
    main()