描述：
You are given two pots, having the volume of A and B liters respectively. The following operations can be performed:
- FILL(i) fill the pot i (1 ≤ i ≤ 2) from the tap;
- DROP(i) empty the pot i to the drain;
- POUR(i,j) pour from pot i to pot j; after this operation either the pot j is full (and there may be some water left in the pot i), or the pot i is empty (and all its contents have been moved to the pot j).
Write a program to find the shortest possible sequence of these operations that will yield exactly C liters of water in one of the pots.
输入：
On the first and only line are the numbers A, B, and C. These are all integers in the range from 1 to 100 and C≤max(A,B).
输出：
The first line of the output must contain the length of the sequence of operations K. The following K lines must each describe one operation. If there are several sequences of minimal length, output any one of them. If the desired result can’t be achieved, the first and only line of the file must contain the word ‘impossible’.
样例输入：
3 5 4
样例输出：
6
FILL(2)
POUR(2,1)
DROP(1)
POUR(2,1)
FILL(2)
POUR(2,1)
翻译：
罐子
描述：
你被给了两个罐子，有液体A和B。请进行以下操作：
- 装满（i） 打开塞子装满罐子i（1<=i<=2）
- 倒掉（i） 将罐子（i）里的液体倒到下水道中
- 倾倒（i ,j） 从罐子i倒入液体到罐子j中；这次操作后罐子j是满的（并且罐子i中可能还剩了水），或者罐子i是空的（它里面所有的液体都被倒入了罐子j中）
写一个程序来找到最短的操作来使C升液体都到一个罐子中。
输入：
第一行并且仅仅有一行是数字A,B,C这些整数从1排列到100，且C<=A,B中的最大值
输出:
输出的第一行一定包含操作次数K的长度。接下来K行一定是描述一次操作的。如果有最短的操作，输出它们当中的任意一个。如果希望得到的结果没有得到，第一行和文件的一行输出‘impo’
样例输入：
3 5 4
样例输出：
6
FILL(2)
POUR(2,1)
DROP(1)
POUR(2,1)
FILL(2)
POUR(2,1)
