Problem H: Hoax or what
Each MalWart supermarket has prepared a promotion scheme run by the
following rules:
 A client who wants to participate in the promotion (aka a sucker)
must write down their phone number on the bill of their
purchase and put the bill into a special urn.

Two bills are selected from the urn at the end of each day: first
the highest bill is selected and then the lowest bill is selected.
The client who paid the largest bill receives a monetary prize equal to
the difference between his bill and the lowest bill of the day.
 Both selected bills are not returned to the urn while all the remaining
ones are kept in the urn for the next day.

MalWart has many clients such that at the end of each day there are
at least two bills in the urn.

It is quite obvious why MalWart is doing this: they sell crappy
products which break quickly and irreparably. They give a shortterm
warranty on their products but in order to obtain a warranty
replacement you need the bill of sale. So if you are gullible enough to
participate in the promotion you will regret it.
Your task is to write a program which takes information
about the bills put into the urn and computes MalWart's cost of the promotion.
The input contains a number of cases.
The first line in each case contains an integer
n, 1<=n<=5000, the number of days of the promotion.
Each of the subsequent n lines contains a sequence of
nonnegative integers separated by whitespace. The numbers in
the (i+1)st line of a case give the data for the ith day.
The first number in each of these lines, k,
0≤k≤10^{5}, is the number of bills and
the subsequent k numbers are positive integers of the bill
amounts. No bill is bigger than 10^{6}.
The total number of all bills is no bigger than 10^{6}.
The case when n = 0 terminates the input and should not be processed.
For each case of input print one number: the total amount paid to the
clients by MalWart as the result of the promotion.
Sample input
5
3 1 2 3
2 1 1
4 10 5 5 1
0
1 2
2
2 1 2
2 1 2
0
Output for sample input
19
2
T. Walen, adapted by P. Rudnicki