<image> There is a container with an inlet and outlet, and the amount of water entering and leaving per unit time is constant. Suppose that starting from a certain moment, water only flows in for the first 5 minutes, then only flows out for the next 2 minutes, and then both flows in and out for the subsequent 15 minutes, just filling the container. Given the function relationship between the water volume \(y\) liters in the container and the time \(x\) minutes as shown in the diagram, the water volume in the container at the 7th minute is ____ liters.