less 0 m false less s n 0 true less s n s m less n m d n 0 n d s n s m d n m gcd n 0 0 gcd n n n gcd n m gcd d n m m less m 0 true less n m true less 2 0 0 false 0 s 1 true 0 d 2 gcd 2 ORIENTED FULL