A person enters a room with 5 doors. One of the doors will lead him to safety and the other 4 will lead him to hell where he will die. In the middle of the room, there are 5 stones lined up in a single file, numbered 1 to 5. These stones will either lie or tell the truth, but the stones have to tell the truth if the stone before it lies and vice versa. For example, if stone 1 lies, stone 2 has to tell the truth. The person does not know anything else about the stones. Also, he cannot ask a direct question to find out if a stone is lying or not. For example, he cannot go up to stone 1 and ask if 1 + 1 is equal to 2. How does he lead himself to safety?