using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        float? floatA = 5;

        float? floatB = 10;

        float? floatC = null;

        float? result = null;

        float? fixedResult = null;

        result = floatA + floatB + floatC;

        if(fixedResult.HasValue)  fixedResult += floatA.HasValue ? floatA : 0; 

            else fixedResult = floatA;

        //if(floatA.HasValue) fixedResult = fixedResult + floatA;

        Console.WriteLine($"Result: {result}");

        Console.WriteLine($"Fixed Result: {fixedResult}");

    }

}