public class DotNetProgram
public DotNetProgram(int a, int b)
public DotNetProgram(int a, int b, int c, int d) : this(a, b)
public static void Main()
DotNetProgram p = new DotNetProgram(5, 10, 15, 20);
Console.WriteLine(p.Sum());
return _a + _b + _c + _d;