public string Test25(int f, int s)
        {
            var first = new OwnBigInteger();

            foreach (var value in f.ToString())
            {
                first.Add(int.Parse(value.ToString()), true);
            }
            first.Print(true);

            var second = new OwnBigInteger();

            foreach (var value in s.ToString())
            {
                second.Add(int.Parse(value.ToString()), true);
            }
            second.Print(true);

            var result = OwnBigInteger.AddInReverseOrder(first, second);

            Console.WriteLine("Result is");
            result.Print(true);
            var test25 = result.ToString();

            return(test25);
        }