As you all know, you are participating in the SYSUCPC (SYSU Constructive Problem Contest) finals. Undoubtedly, the Constructive Kingdom of Sun Yat-sen University is eager for you to tackle some related problems.
Given a string $$$S$$$ containing only lowercase letters, determine the maximum number of disjoint subsequences of length $$$4$$$ that can be formed, such that all subsequences are sysu. Formally, a subsequence of a string $$$S$$$ is a subset of characters of $$$S$$$ that read from left to right.
A greedy algorithm is currently used: each time, starting from the end, an unused u is considered, and it is matched with nearest unused s,y,s sequentially to form a qualified subsequence, which is then removed.
You are now requested to provide a string $$$S$$$ such that the answer obtained by the greedy method is $$$x$$$, while the correct answer is $$$y$$$. If no such $$$S$$$ exists, output $$$-1$$$.
The only line contains two integers $$$x,y(1\leq x,y\leq 10^5)$$$.
A string $$$S$$$ such that the answer obtained by the greedy method is $$$x$$$, while the correct answer is $$$y$$$. If no such $$$S$$$ exists, output $$$-1$$$. The length of $$$S$$$ must not exceed $$$4\times 10^5$$$.
1 1
ilovesysu
2 1
-1
