✅ Override (abstract) getter-only property with a setter

public class Base {
    public abstract int Count { get; }
}

public class Derived : Base {
    // #1
    public override int Count { get; set; } // CS0546: Cannot override because no 'set' accessor

    // #2
    // CS0106: The 'override' modifier is not valid for this item
    // CS0538: 'Base' in explicit implementation is not an interface
    override Base.Count => Count;
    public new int Count { get; set; }
}