I think it must be three.
1 gives to 2 - 0
2 gives to 3 - 0
3 gives to 4 - 1
4 gives to 5 - 2
5 gives to 6 - 2
6 gives to 7 - 2
7 gives to 8 - 3

I cant understand how it can be 4.
Even Tolstobrov_Anatoliy[Ivanovo SPU] gave some tests
(http://acm.timus.ru/forum/thread.aspx?space=1&num=1117&id=11659&upd=632589453091063750)
and there are such tests:
1 7 2
1 8 4
So I'm right up to the 7'th employee. Then we add 1.

Thank.

1 gives to 2 - 0
2 gives to 3 - 0
3 gives to 4 - 1
4 gives to 5 - 1
5 gives to 6 - 0
6 gives to 7 - 0
7 gives to 8 - 2

My awfull mistake!!!
Forgot, that
the message delivery takes an amount of days that is equal to the number of intermediate employees between the sender and recipient.
Thank you.