The Light Cups

Melisandre,often referred to as The Red Woman,is a priestess of the Lord of Light. She is advising Stannis Baratheon in his campaign to take the Iron Throne.For this embarkment she needs to raise an army of black demons. There are N light cups aligned in a row. The black demons will rise only when all the N cups are lit. Initially some of the cups are lit. The cups which are not lit can be lit onl