Console-算法-一个偶数总能表示为两个素数之和

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int a, b, c, d;
            a = Convert.ToInt32(Console.ReadLine());
            for (b = 3; b <= a / 2; b += 2)
            {
                for (c = 2; c <= Math.Sqrt(b); c++)
                {
                    if (b % c == 0)
                    {
                        break;
                    }
                    if (c > Math.Sqrt(b))
                    {
                        d = a - b;
                    }
                    else
                    {
                        break;
                    }
                    for (c = 2; c <= Math.Sqrt(d); c++)
                    {
                        if (d % c == 0)
                        {
                            break;
                        }
                        if (c > Math.Sqrt(d))
                        {
                            Console.WriteLine("{0}={1}+{2}",a,b,d);
                        }
                    }
                }
            }
        }
    }
}