using System;

public class Test
{
    public static void Main()
    {
    	new Child1();
    	new Child2();
    }
}

class Parent
{
    public Parent() { DoSomething(); }
    protected virtual void DoSomething() {}
}

class Child1 : Parent
{
    private string foo = "FOO";
    protected override void DoSomething() => Console.WriteLine(foo.ToLower());
}

class Child2 : Parent
{
    private string foo;
    public Child2() { foo = "FOO"; }
    protected override void DoSomething() => Console.WriteLine(foo.ToLower());
}