从孙子往上数到根

运行下面这段程序，填写它打印出来的结果。

PS = [
    # PID, PPID, 状态, CPU%, 内存KB, 名字
    (1,   0,  "Ss", 0.0,   3148, "bash"),
    (12,  1,  "Ss", 0.0,   1680, "收数据.sh"),
    (13,  1,  "Ss", 0.0,   1640, "看门狗.sh"),
    (14,  1,  "Ts", 0.0,   1576, "补台账.sh"),
    (16,  13, "S",  0.0,   1596, "发通知"),
    (17,  12, "R",  51.3,  3152, "算账"),
    (18,  12, "S",  0.2, 100208, "建索引"),
]

by = dict((r[0], r) for r in PS)
cur = 16
chain = []
while cur in by:
    chain.append(str(cur))
    cur = by[cur][1]
print("-".join(chain) + "/" + str(len(chain)))