There is a drum full of milk.
People come for buying milk in the range of 1-40 litres.
You can have only 4 cans to draw milk out of drum. Tell me what should be the measurement of these four cans so that you can measure any amount of milk in the range of 1-40 litres.
Note that the cans cannot be used more than once to refill from the drum.
Output the numbers in ascending order space separated.