Hoax or what

Each Mal-Wart supermarket has prepared a promotion scheme run by the fol- lowing 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. • Mal-Wart 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 Mal-Wart is doing this: they sell crappy products which break quickly and irreparably. They give a short-term 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 Mal-Wart’s cost of the promotion. Input 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 non-negative integers separated by whitespace. The numbers in the (i + 1)-st line of a case give the data for the i-th day. The first number in each of these lines, k, 0 ≤ k ≤ 105, is the number of bills and the subsequent k numbers are positive integers of the bill amounts. No bill is bigger than 106. The total number of all bills is no bigger than 106. The case when n = 0 terminates the input and should not be processed. Output For each case of input print one number: the total amount paid to the clients by Mal-Wart as the result of the promotion. Sample Input 5 3123 211 4 10 5 5 1 0

2/2 12 2 212 212 0 Sample Output 19 2