Winter in Yekaterinburg is the longest time of the year. And everyone 
spends long winter evenings in his own way. For example, Eugene creates 
computer games in the evenings. His current game has a very simple game 
play — user controls a spaceship flying in 3D space. To test the 
mechanics of the movement of his spaceship Eugene wants to solve 
the following problem: can his spaceship, moving in a straight line, fly 
through the points A and B, then make a turn at 90°, and 
then fly through the points C and D, continuing to move in a straight 
line. The points A, B, C, D should be visited by the spaceship in 
just that order, the turning point may coincide with the point B or the 
point C. The spaceship should be considered as a material point.
Input
There are four lines, each containing integers xi, yi, zi that 
are the coordinates of the points A, B, C, D respectively (−106 
≤ xi, yi, zi ≤ 106). All points are pairwise 
different.
 
Output
If the spaceship can fly through the data points, output “Valid”, 
otherwise output “Invalid”. 
Sample
| input | output | 
|---|
| -2 0 0
-1 0 0
0 1 0
0 2 0
 | Valid
 | 
Problem Author: Denis Dublennykh
Problem Source: Open Ural FU Personal Contest 2014