public static int pickingNumbers(List<int> input)
    {
        int maxNumber = 0;
        int buildingArray = 0;
        input.Sort();
        for (int i = input.Count-1; i > -1; i--)
        {
            if ((input[i + buildingArray]) == input[i] + 1 || input[i + buildingArray] == input[i])
            {

                buildingArray++;
                if (i == 0)
                {
                    if (buildingArray > maxNumber)
                    {
                        maxNumber = buildingArray;
                    }
                }
            } else
            {
                if (buildingArray > maxNumber)
                {
                    maxNumber = buildingArray;
                }
                i = i + buildingArray;
                buildingArray = 0;

            }


        }
        return maxNumber;
    }