bool IsCoord(int x1, int y1, int x2, int y2, int x3, int y3)
{
    // Check if three points can form a triangle (not collinear)
    // Using cross product: (x2-x1)*(y3-y1) - (y2-y1)*(x3-x1) != 0
    int area2 = (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1);
    return area2 != 0;
}