//C#
string st="1+2+3+4+5+6";

//C#
string st="1+2+3+4+5+6";

class Program
    {
        static string input;

        static void Main(string[] args)
        {
            input = "123456";
            foreach (string s in Permutate(input.Length - 1))
                Console.WriteLine(s);
            Console.ReadKey();
        }

        static IEnumerable<string> Permutate(int length)
        {
            string[] operators = { "", "+", "-", "*", "/" };
            if (length <= 1)
                foreach (string c in operators)
                {
                    string frs = input.Substring(0, 1);
                    string dig = input.Substring(length, 1);
                    yield return frs + c + dig;
                }
            else
                foreach (string p in Permutate(length - 1))
                    foreach (string c in operators)
                    {
                        string dig = input.Substring(length, 1);
                        yield return p + c + dig;
                    }
        }

    }

static object Calc(string formula)
        {            
            string s1 = "/0";            
            bool b = formula.Contains(s1);
            if (b==false)
            {
                DataTable table = new DataTable();
                table.Columns.Add("sum", typeof(decimal)).Expression = formula;
                DataRow row = table.NewRow();
                table.Rows.Add(row);
                return table.Rows[0]["sum"];
            }
            else return "Division by zero";
        }