A circular island has a diameter of 80 meters, a circular flower bed with a diameter of 10 meters in the middle, and lawns elsewhere. What is the lawn area?
一个圆岛的直径是80米，中间是一个直径为10米的圆形花坛，其他地方是草坪．草坪面积是多少？
<result>49_455</result>