Of the 10 possible molds, only two can have a base that is a square. That is, a base where the all 4 sides are equal. In this case, you can make the molds:
1,1,28 ; where the base is a 1x1 square with height 28 cm.
and
2,2,7 ; where the base is a 2x2 square with height 7 cm.