public static void Main()
Console.WriteLine("Enter the first number");
int a = Int32.Parse(Console.ReadLine());
Console.WriteLine("Enter the second number");
int b = Int32.Parse(Console.ReadLine());
Console.WriteLine("Enter the operation - Enter +,-,*,/");
int op = Int32.Parse(Console.ReadLine());
Console.WriteLine("Sum =" + c);
Console.WriteLine("Difference =" + c);
Console.WriteLine("Product =" + c);
Console.WriteLine("Quotient =" + c);
Console.WriteLine("Invalid input");