A rope is wound around a hollow cylinder and another is wound around a solid cylinder. The surfaces of the cylinders have some friction. The solid cylinder is 20 times heavier than the hollow cylinder. The ropes are pulled with a constant force of 50 N. Assume that the cylinders acquire an equal angular acceleration. The number of turns on the hollow cylinder is four. If the radius of each cylinder is 14 cm, then what is the length of the rope wound around the solid cylinder?