This uses an ASCII HYPHEN-MINUS:
{{coord|-1|N|1|E}}
This uses an Unicode MINUS SIGN (U+2212):
{{coord|−1|N|1|E}}
This uses an Unicode MINUS SIGN (U+2212), as an HTML entity:
Here's a direct URL for the geohack page:
Here's one using MINUS SIGN as literal UTF-8:
And as an entity: