3月11日 判断输入的年月日是否正确

//判断年月日是否正确；
            for (; ; )
            {
                Console.Write("请输入年份：");
                int a = int.Parse(Console.ReadLine());
                if (a >= 0 && a <= 9999)
                {
                    Console.Write("请输入月份：");
                    for (; ; )
                    {
                        int b = int.Parse(Console.ReadLine());
                        if (b <= 12 && b > 0)
                        {
                            Console.Write("请输入日期");
                            for (; ; )
                            {
                                int c = int.Parse(Console.ReadLine());
                                if (c > 0 && c <= 31)
                                {
                                    if (b == 1 || b == 3 || b == 5 || b == 7 || b == 8 || b == 10 || b == 12)
                                    {
                                        if (c > 0 && c <= 31)
                                        {
                                            Console.WriteLine("您输入的日期为" + a + "年" + b + "月" + c + "日");
                                            break;
                                        }
                                        else
                                        {
                                            Console.Write("您输入的日期有误，请重新输入：");
                                        }
                                    }
                                    if (b == 4 || b == 6 || b == 9 || b == 11)
                                    {
                                        if (c > 0 && c <= 30)
                                        {
                                            Console.WriteLine("您输入的日期为" + a + "年" + b + "月" + c + "日");
                                            break;
                                        }
                                        else
                                        {
                                            Console.WriteLine("您输入的日期有误，请重新输入：");
                                        }
                                    }
                                    if (b == 2)
                                    {
                                        if (a % 4 == 0 && a % 100 != 0 || a % 400 == 0)
                                        {
                                            if (c > 0 && c <= 29)
                                            {
                                                Console.WriteLine("您输入的日期为" + a + "年" + b + "月" + c + "日");
                                                break;
                                            }
                                            else
                                            {
                                                Console.WriteLine("您输入的日期有误，请重新输入：");
                                            }
                                        }
                                        else
                                        {
                                            if (c > 0 && c <= 28)
                                            {
                                                Console.WriteLine("您输入的日期为" + a + "年" + b + "月" + c + "日");
                                                break;
                                            }
                                            else
                                            {
                                                Console.WriteLine("您输入的日期有误，请重新输入：");
                                            }
                                        }
                                    }

                                }
                                else
                                {
                                    Console.WriteLine("您输入的日期有误，请重新输入：");
                                }

                            }
                            break;
                        }
                        else
                        {
                            Console.WriteLine("您输入的月份有误，请重新输入：");
                        }

                    }
                    break;
                }
                else
                {
                    Console.WriteLine("您输入的年份有误，请重新输入：");
                }
            }
            Console.ReadLine();