Translate the text above into English, please retain the original text's line breaks and format, and output the translation result directly.
Note: The provided text "性质：" translates to "Properties:" in English. However, since the instruction is part of the meta-context and not the content to be translated, the direct translation of the provided content is as follows:
Properties:
A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.
Solution
None
Translate the text above into English, please retain the original text's line breaks and format, and output the translation result directly.
Note: The provided instruction is a meta-instruction and not part of the text to be translated. Since the text to be translated is "None", the translation is also "None". Here is the formatted output as requested:
None
Want a route through all this instead of an archive? The track
puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.
Source: NuminaMath-1.5,
licensed Apache-2.0.
Statement and solution reproduced as published; topic and difficulty added by this site.