using System;

interface ILogger
{
    void Log(string message);
}

class ConsoleLogger : ILogger
{
    public void Log(string message) => Console.WriteLine($"Console log: {message}");
}

class FileLogger : ILogger
{
    public void Log(string message) => File.AppendAllText("log.txt", $"File log: {message}{Environment.NewLine}");
}

class DatabaseLogger : ILogger
{
    public void Log(string message) => Console.WriteLine($"Database log: {message}");
}

class Application
{
    private readonly ILogger _logger;
    public Application(ILogger logger) => _logger = logger;
    public void Run() => _logger.Log("Application started");
}

class Program
{
    static void Main()
    {
        ILogger logger = new FileLogger();
        Application app = new Application(logger);
        app.Run();
    }
}