A rectangle has width 10 units and height 6 units. Two line segments are drawn inside the rectangle. The first segment connects a point on the left side, 2 units from the top, to a point on the right side, 2 units from the bottom. The second segment connects a point on the top side, 2 units from the left, to a point on the bottom side, 2 units from the right. Find the area of the shaded region, which consists of the four corner triangles formed by these line segments and the sides of the rectangle.