By Lucas Maciel, UFMG Brazil
King Leonardo II is very worried about violence in Syldavia. Everybody is terrified, saying that this situation must end. So, Leonardo II ask for his advisors remake the street maps of his Kingdom, in the way that is no longer possible travel from one city to another with more than one path (could have no path, but couldn't have more than one).
Therefore, King Leonardo II of Syldavia ask you to make a program that verify if a created map is safe or not. And yes, he ask you to do that, because you are in a contest of 5 hours programming, so it will very easy for you! If you don't want do that job, you could also format the advisor's personal computer...
All streets are two-way. There is no warranty about the graph be connected. Could have more than one street connecting the same pair of cities.
The input is composed of many test cases separated by a blank line. Each test case start with two integers, N and M, that represent the number of cities and the streets, respectively (1 ≤ N ≤ 10000, 1 ≤ M ≤ (N * (N-1)) ÷ 2). The next M lines have two integers, A and B, means that have one street connecting the cities A and B (1 ≤ A, B ≤ N).
For each test case output one line having a string "Seguro" if the Syldavia map is safe according with Leonardo II or "Inseguro" otherwise.
In the last case, there are two possible paths to leave the city 1 and come to itself. The first one is still there, and the second is walk in the street that connect it to itself. That's why this map in unsafe.
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