public void Test_FindMissingNumber(string input, int expected) { var result = NumberUtilities.FindMissingNumber(input); Assert.That(result, Is.EqualTo(expected)); var query = input .Split(' ') .Select(Int32.Parse) .GroupBy(s => s) .OrderBy(s => s.Count()) .Select(x => new { Number = x.Key, RepetitionCount = x.Count() }); foreach (var item in query) { Console.WriteLine($"Number: {item.Number}, repetitionCount: {item.RepetitionCount}"); } }