public void addExtra(string make, string model, int datefrom, int dateto)
{
for (int i = 0; i < Counter; i++)
{
if (Make[i] == make && Model[i] == model && Datefrom[i] == datefrom && Dateto[i] == dateto)
{
return;
}
}
Model.Add(model);
Make.Add(make);
Datefrom.Add(datefrom);
Dateto.Add(dateto);
Counter++;
}