#include<iostream>#include <fstream>#include <set>usingnamespacestd;
voidfastio()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
}
intmain()
{
fastio();
#ifndef ONLINE_JUDGEifstreamfin("f:\\OJ\\uva_in.txt");
streambuf*back=cin.rdbuf(fin.rdbuf());
#endifintn;
while ((cin>>n) &&n) {
unsignedlonglongres=0;
multiset<int>bills;
for (inti=0; i<n; i++) {
intk;
cin>>k;
for (intj=0; j<k; j++) {
inttmp;
cin>>tmp;
bills.insert(tmp);
            }
autobegin=bills.begin();
autoend=bills.end();
--end;
res+=*end-*begin;
bills.erase(begin); bills.erase(end);
        }
cout<<res<<endl;
    }
#ifndef ONLINE_JUDGEcin.rdbuf(back);
#endifreturn0;
}