int isInInterval(point_t *P1, point_t *P2, point_t *a){
    int ans1 = (((DoubleRound(P1->x) < DoubleRound(a->x)) && (DoubleRound(a->x) <= DoubleRound(P2->x)))
        ||((DoubleRound(P1->y) < DoubleRound(a->y)) && (DoubleRound(a->y) <= DoubleRound(P2->y))));
    int ans2 = (((DoubleRound(P2->x) <= DoubleRound(a->x)) && (DoubleRound(a->x) < DoubleRound(P1->x)))
        || ((DoubleRound(P2->y) <= DoubleRound(a->y)) && (DoubleRound(a->y) < DoubleRound(P1->y))));
    return (ans1 || ans2);
}