<image>A container equipped with an inlet pipe and an outlet pipe starts to fill with water by opening the inlet pipe. After a period of time, the outlet pipe is opened to let the water out. At the 12-minute mark, the inlet pipe is closed. During the time the inlet pipe is open, the relationship between the amount of water \( y \) (in liters) in the container and the time \( x \) (in minutes) is shown in the figure. After closing the inlet pipe, it takes _____ minutes for the container to be completely emptied of water. 