三个和尚三个鬼过河。小船最多两个乘坐，最少一个。任何时候，在两岸边如果鬼的数量多于和尚，那么和尚就吃掉鬼，任务失败。(Please help the 3 cannibals and 3 missionaries to move to the other side of the lake.notice that:when there is on one side more cannibals than missionaries,the eat them)