private void FillCityCodes()
{
int i = 0;
foreach (var item in this.Provinces)
{
item.ProvinceId = Provinces.IndexOf(item) + 1;
item.Cities.ForEach(a => a.ProvinceId = item.ProvinceId);
item.Cities.ForEach(a => a.CityId = ++i);
}
}