How to convert Reference type into value type

I have written the following code but the when i enter value after that its the value 0 why please help me,
how can i add this two number



class program
{
int a,b,sum;

public int Sumation(int a,int b)

{
sum=a+b;
return sum;

}

static void Main()
{
int c,d,e;

Console.WriteLine("Enter Value of C & D");
c=int.parse(Console.ReadLine());
d=int.parse(Console.ReadLine());

Program p =new Program();

e=p.Sumation(c,d);
Console.WriteLine("Sum of two value is: "+ e);
console.ReadLine();

}

}