说明：  现有公园游船租赁处请你编写一个租船管理系统。当游客租船时，管理员输入船号并按下S键，系统开始计时；当游客还船时，管理员输入船号并按下E键，系统结束计时。船号为不超过100的正整数。当管理员将0作为船号输入时，表示一天租船工作结束，系统应输出当天的游客租船次数和 平均租船时间。
(Existing Park Service boat rental please prepare a charter management system. When the tourists when charter, the administrator enter the ship and press the S key number, the system timer when tourists also ship when the ship No. administrator and press Enter E key, the system the end of time. No. vessels of not more than 100 positive integer. When the administrator will enter the number 0 as a ship when that one day the end of a charter, the system should output the number of day visitors and average charter charter time.)