static void Main(string[] args)
{
do
{
int n;
n = SoNguyen.NhapSoNguyenDuong("Nhap n=");
Console.Write("Tong cac chu so chan cua " + n + " la " + TinhToan.tong(n));
} while (SoNguyen.NhapSoNguyen("\nTiep tuc (1.Tiep, 0.Khong)") != 0);
}