Bread

Some chefs go for a tour lasting N days. They take packages of bread for food. Each package has K pieces of breads. On the ith day, they eat Ai pieces of bread. Unfortunately, chefs are very lazy people, and they always forget to close the package of breads, so each day the last piece of bread becomes exposed to mold (a fungus), and is no longer suitable for eating. Such a bad piece is not eaten,