GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
#g2 f1 z1 c1 2x 2 0 1 -1 1 2x 2 0 1 1 0 2x 2 2 -1 -1 2 2x2 -1 0 0 -1 2x2 -1 0 0 -1 2^2 *3= 12 %order of the group;