How many 90 degree elbows in vent?

Can you come out of the stove with a 90 degree elbow and then out with another 90 and then up with another 90? Or will that be to many?

i would try to avoid it if possible , or maybe use 2 45 degree elbows if doable. 90 degree elbows can rob up to 15% of airflow and back to back is worst case in that effect , it would likely work but you would build ash more rapidly and its not as easy to clean. most pellet installs can handle 3 elbows , but as a rule i try to limit them as much as possible. hope this helps ya.