freetr
static void freetr(Node *);
freetr(p1);
freetr(left(p));
freetr(left(p));
freetr(right(p));
static void freetr(NODE *p);
freetr(p1); /* add this when alloc works */
freetr(left(p));
freetr(left(p));
freetr(right(p));