Integer Points#1038
A polygon on the plane is given by the coordinates of its vertices. You are required to count the number of points with integer coordinates that lie strictly inside this polygon.
The first line contains (3 \leq N \leq 1000) — the number of vertices of the polygon. The next lines contain the coordinates X_i, Y_i of the vertices in clockwise order. X_i and Y_i are integers with absolute value not greater than .
— the required number of points, with no leading zeros.
Example 1