Building leveling problem

It takes two people to finish. The concrete steps are as follows: 1, set the elevation between the tower crane foundation and a wall mentioned by your master; 2. Find someone to take a ruler, mark the bottom of the ruler or mark it with a pen (1), and aim the bottom or mark at a meter point on the wall, which must be aligned and vertical; 3. Then look at your ruler with a level. Then take your ruler and walk to the four piles of the tower crane foundation, which should be vertical. By moving the ruler up and down, you can clearly see the red mark (No.2 mark) you marked on the level. Then don't move, look down, find the mark (No.1), and extend this mark 1 to your stake, which is the one-meter horizontal line your master wants. All right, it's done. Better check it again. Report to your master.