6001: POJ2513 - Colored Sticks
[Creator : ]
Description
You are given a bunch of wooden sticks. Each endpoint of each stick is colored with some color. Is it possible to align the sticks in a straight line such that the colors of the endpoints that touch are of the same color?
Input
Input is a sequence of lines, each line contains two words, separated by spaces, giving the colors of the endpoints of one stick. A word is a sequence of lowercase letters no longer than $10$ characters. There is no more than $250,000$ sticks.
Output
If the sticks can be aligned in the desired way, output a single line saying Possible, otherwise output Impossible.
Sample 1 Input
blue red
red violet
cyan blue
blue magenta
magenta cyan
Sample 1 Output
Possible