- Time limit: 1.00 s
- Memory limit: 512 MB
A game has n levels and m teleportes between them. You win the game if you move from level 1 to level n using every teleporter exactly once.
Can you win the game, and what is a possible way to do it?
The first input line has two integers n and m: the number of levels and teleporters. The levels are numbered 1,2,\dots,n.
Then, there are m lines describing the teleporters. Each line has two integers a and b: there is a teleporter from level a to level b.
You can assume that each pair (a,b) in the input is distinct.
Print m+1 integers: the sequence in which you visit the levels during the game. You can print any valid solution.
If there are no solutions, print "IMPOSSIBLE".
- 2 \le n \le 10^5
- 1 \le m \le 2 \cdot 10^5
- 1 \le a,b \le n
5 6 1 2 1 3 2 4 2 5 3 1 4 2
1 3 1 2 4 2 5