How to get an Not Empty Instance back ?

public static TheQFromDB CalculateMaxVal(List input)

{

TheQFromDB Q = new TheQFromDB();

double maxValue = double.MinValue;

foreach (var item in input)

{

if (item.SecondsDiff > maxValue)

maxValue = item.SecondsDiff;

Q.MaxValue = maxValue;

}

input.Add(Q);

Console.WriteLine(Q.MaxValue);

return Q;

 

in this Ex here i have a List from Type TheQFromDB and insaid (input) several properties one of them is SecondsDiff .. i want get the class TheQfromDB back but with this code iam getting an Empty instance which call here Q .