Problem 17:  Point inside triangle.

When is a point (s,t) inside a triangle with vertices (x1, y1), 
(x2, y2), (x3, y3)??  For this problem, the input will contain 20 
lines containing coordinate pairs:
     three lines with coordinates of three vertices of first triangle
     seven lines, each with coordinates of a point to be tested therein
     three lines with coordinates of three vertices of second triangle
     seven lines, each with coordinates of a point to be tested therein

For example, if the first five lines of input were
     3   2
     6  10
    15   7
     5   7
    14   6
the corresponding output would be
     5   7  is  inside triangle  1
    14   6  is outside triangle  1

Spacing of the output is not important, but you must have the words
"is", "inside" or "outside", and "triangle" in your output, just as
in the example.

The vertices of the triangle, and the test point, are guaranteed to
be integers.