You are given a traditional balance scale with two pans (no reading) and 6 boxes with the following properties:
1) the weight of each box is a positive integer number
2) if you put any number of boxes on the left pan of the scale and any number of boxes on the right pan of the scale, the scale is never in balance.
Note it is not required to use all boxes for weighing, but at least one box is on a pan.
What is the minimum weight of the heaviest box?
Example: weight 1,2,4,8,16,32 is a possibility with weight 32 being the heaviest box. Find a lower weight than 32 for the heaviest box!