MINUS number
-number

Outputs the negative of its input.

The minus sign means unary minus if it is immediately preceded by something requiring an input, or preceded by a space and followed by a non-space. There is a difference in binding strength between the two forms:

MINUS 3 + 4 means -(3+4)

- 3 + 4 means (-3)+4

SHOW 2 - -3
5

SHOW 2 - MINUS 3
5