static void Main(string[] args)
{
Arith arith = new Arith();
int back1 = arith.AddCli(1, 2);
Console.WriteLine(back1.ToString());
int back2 = arith.SubCli(3, 4);
Console.WriteLine(back2.ToString());
int back3 = arith.MulCli(4, 5);
Console.WriteLine(back3.ToString());
int back4 = arith.DivCli(8, 4);
Console.WriteLine(back4.ToString());
Console.ReadLine();
}