DMPG '19 B5 - Triangles
View as PDFThere are  points labelled from 
 to 
. The point labelled 
 is located at 
. These 
 points are coloured such that the point labelled 
 has colour 
. There are only two colours, red or blue. If 
 is 
, the point is red and if 
 is 
, the point is blue. It is guaranteed that no two have the same coordinates. Can you choose 
 of the 
 points such that none of the other 
 points lie within the interior of the (possibly degenerate) triangle formed by the 
 points and such that the colours of the 
 points are not all the same? A point on the boundary of the triangle is not considered within the interior of the triangle for this problem. In particular, choosing 
 collinear points will guarantee no other points in its interior.
Constraints
 for all 
 for all 
Input Specification
The first line contains a single integer, .
The next  lines each contain three space-separated integers, 
, 
, and 
.
Output Specification
If it is not possible to find  such points, output 
-1. Otherwise, print three space-separated integers i j k on a single line representing the three points chosen. If there are multiple possibilities, any triplet will be accepted. The triplet does not need to be written in any particular order.
Sample Input 1
6
1 1 1
7 7 2
1 7 1
7 1 1
2 3 1
6 5 1
Sample Output 1
2 3 5
Sample Input 2
4
1 1 1
1 2 2
1 3 1
1 4 1
Sample Output 2
1 2 4
                    
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