using System;

class Program {
    static void Main(string[] args) {
        Console.WriteLine("Hello, C#!");
        
        string name = "Alice";
        int age = 25;
        double salary = 75000.50;
        
        Console.WriteLine($"{name} is {age} years old");
        
        // Nullable types
        int? maybeNull = null;
        Console.WriteLine(maybeNull ?? -1);
        
        // Var keyword
        var message = "type inferred";
        
        // Pattern matching
        object obj = "Hello";
        if (obj is string str) {
            Console.WriteLine($"Length: {str.Length}");
        }
    }
}