public static void Main()
Console.WriteLine("insert number one");
int number1 = Int16.Parse(Console.ReadLine());
Console.WriteLine("insert number two");
int number2 = Int16.Parse(Console.ReadLine());
Console.WriteLine("insert number three");
int number3 = Int16.Parse(Console.ReadLine());
if ((number1 + number2 + number3) %3 == 0){
if (number1 - number2 != 1 && number2 - number3 !=1 && number3 - number1 !=1){
Console.WriteLine(Convert.ToString(number1)+Convert.ToString(number2)+Convert.ToString(number3)+" IS A VALID SITESWAP");
Console.WriteLine("INVALID SITESWAP");