Signed symmetric group

A signed symmetric group is a way of arranging a group of numbers so the same pattern appears when the group is flipped or turned upside down. It looks like a regular group of numbers, but one or more of the numbers has either a "+" or "-" sign in front of it to indicate if it should be switched around or not. For example, the signed symmetric group [3, -2, 1] would be mirrored around the middle number (2) when it was flipped, so the flipped version of the group would be [-3, 2, -1].