There are weights of 1, 2, 4, 5, and 7 grams each. One of the weights is lost. As a result, the balance cannot weigh 10 grams (the weight must be placed on one side of the balance). How much does the lost weight weigh? gram.
有l，2，4，5，7克的砝码各一个，丢失了其中一个砝码，结果天平无法称出10克的重量(砝码必须放在天平的一边)，丢失的砝码重多少克．
<result>1</result>