One is straight, the other is back, hunchback is generally caused by unreasonable posture for a long time, so you can stand against the wall first, the second one can do standing exercises by standing on a book with your forefoot on a book of 2 cm, and your feet touch the ground, the third one can walk with a body orthopedic shoes, also called negative heel shoes, and the fourth one can do forward stretching: supine, with your feet shoulder width apart. It doesn't matter if you don't straighten your arm at first. The longer you keep them, the better.