c# 输出两个三角形（菱形）

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Type in a int:");
            int input = Convert.ToInt32(Console.ReadLine()) ;
           // Console.WriteLine(input);
            if (input < 0)
                Console.WriteLine("input a -int!");
            else
            {
                if (input == 0)
                    Console.WriteLine("input 0");
                else
                {
                    for (int i = 0; i < input; i++)
                    {
                        for (int j = 0; j <= input-i; j++)
                            Console.Write(" ");
                        for(int k=0;k<2*i+1;k++)
                        Console.Write("*");
                     Console.WriteLine();

                    }
                    for (int i = 1; i < input; i++)
                    {
                        for (int j = 0; j <= i+1; j++)
                            Console.Write(" ");
                        for (int k = 0; k < 2*input-2 * i - 1; k++)
                            Console.Write("*");
                        Console.WriteLine();

                    }
 
 

                }
            }
            Console.Read();
        }
    }
}