一个偶数等于两个奇数之和，求组成偶数E的两个奇数的所有组合

    class Program
    {
        static void Main(string[] args)
        {
            //退出条件
            bool exit = true;
            //一直循环直到退出条件为fals
            while (exit)
            {
                //goto到开始
            start:
                Console.WriteLine("Enter a even number:");
                string a = Console.ReadLine();
                int E;
                //移除首尾空白并转换为小写
                if (a.ToLower().Trim() == "exit")
                {
                    //退出
                    exit = false;
                }
                //判断输入是否为数字
                bool result = int.TryParse(a, out E);
                if (result)
                {
                    //如果数字为0或者是偶数跳转到开始重新输入
                    while (E % 2 != 0 || E == 0)
                    {
                        goto start;
                    }
                    for (int i = 1; i < E; i++)
                    {
                        while (i % 2 != 0 && i + i < E)
                        {
                            Console.WriteLine("{0}+{1}={2}", i, E - i, E);
                            break;
                        }
                    }
                }
            }
        }
    }