Alice and Bob decided to eat some fruit. In the kitchen they found a large bag of oranges and apples. Alice immediately took an orange for herself, Bob took an apple. To make the process of sharing the remaining fruit more fun, the friends decided to play a game. They put multiple cards and on each one they wrote a letter, either 'A', or the letter 'B'. Then they began to remove the cards one by one from left to right, every time they removed a card with the letter 'A', Alice gave Bob all the fruits she had at that moment and took out of the bag as many apples and as many oranges as she had before. Thus the number of oranges and apples Alice had, did not change. If the card had written letter 'B', then Bob did the same, that is, he gave Alice all the fruit that he had, and took from the bag the same set of fruit. After the last card way removed, all the fruit in the bag were over.
You know how many oranges and apples was in the bag at first. Your task is to find any sequence of cards that Alice and Bob could have played with.
The first line of the input contains two integers, x, y (1 ≤ x, y ≤ 1018, xy > 1) — the number of oranges and apples that were initially in the bag.
Print any sequence of cards that would meet the problem conditions as a compressed string of characters 'A' and 'B. That means that you need to replace the segments of identical consecutive characters by the number of repetitions of the characters and the actual character. For example, string AAABAABBB should be replaced by string 3A1B2A3B, but cannot be replaced by 2A1A1B2A3B or by3AB2A3B. See the samples for clarifications of the output format. The string that you print should consist of at most 106 characters. It is guaranteed that if the answer exists, its compressed representation exists, consisting of at most 106 characters. If there are several possible answers, you are allowed to print any of them.
If the sequence of cards that meet the problem statement does not not exist, print a single word Impossible.
1 4
3B
2 2
Impossible
3 2
1A1B
In the first sample, if the row contained three cards with letter 'B', then Bob should give one apple to Alice three times. So, in the end of the game Alice has one orange and three apples, and Bob has one apple, in total it is one orange and four apples.
In second sample, there is no answer since one card is not enough for game to finish, and two cards will produce at least three apples or three oranges.
In the third sample, cards contain letters 'AB', so after removing the first card Bob has one orange and one apple, and after removal of second card Alice has two oranges and one apple. So, in total it is three oranges and two apples.
题目大意：有一堆橘子和一堆苹果，初始时Alice拿一个橘子，Bob拿一个苹果。有两种操作，一种是Alice把她所有的水果给Bob，然后从水果堆里拿相同数量的水果，使得她拥有的苹果数和橘子数都不变，另一种操作就是让Bob做同样的事情，当水果被拿光时结束。求一个能恰好把所有水果拿完的操作序列。
这样的操作可以转化为用辗转相除法求gcd的过程，具体的原因自己看官方题解吧。
代码在此。
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