def convert_to_obj(vert, tri):
    """
    Convert verts and faces to an OBJ file.

    Arguments:
        vert (int[]): List of verts
        tri (int[]): List of faces
    """
    res = ""
    for vert in vert:
        res += ("v {} {} {}\n".format(vert[0], vert[1], vert[2]))
    for face in tri:
        res += ("f {} {} {}\n".format(*(face + 1)))
    return res