public static void Main()
Console.WriteLine("Enter number");
val1 = int.Parse(Console.ReadLine());
Console.WriteLine("Enter number");
val2 = int.Parse(Console.ReadLine());
Console.WriteLine("Enter operation");
op = char.Parse(Console.ReadLine());
Console.WriteLine("Invalid Input");
Console.WriteLine("Answer: " + ans);
Console.WriteLine("Would you like to continue? (Y/N)");
res = char.Parse(Console.ReadLine());
while (res == 'Y' || res == 'y');