56. In the figure, the two circles have only one common point $A$, the diameter of the larger circle is 48 cm, and the diameter of the smaller circle is 30 cm. Two ants start from point $A$ at the same time and move in the direction indicated by the arrows at the same speed, each along one of the circles. When the ant on the smaller circle has crawled $\qquad$ laps, the two ants are farthest apart for the first time.
Answer: 4