delegate int Operation(int val1, int val2);

public int Add(int val1, int val2)

{

return val1 + val2;

}

public int Subtract (int val1, int val2)

{

return val1- val2;

}

public void Perform()

{

Operation Oper;

Console.WriteLine("Enter + or - ");

string optor = Console.ReadLine();

Console.WriteLine("Enter 2 operands"); 

string opnd1 = Console.ReadLine();

string opnd2 = Console.ReadLine(); 

int val1 = Convert.ToInt32 (opnd1);

int val2 = Convert.ToInt32 (opnd2); 

if (optor == "+")

Oper = new Operation(Add);

else

Oper = new Operation(Subtract); 

Console.WriteLine(" Result = {0}", Oper(val1, val2));

}