Problem Formatting Guidelines

This guideline is largely based on BOJ formatting guide. This guideline may be different from the document.

Don't use <br>. Use <p> to divide paragraphs.
Don't use empty lines.
Recommend using mathjax for math expressions.
Don't change font size. Headings <h1> to <h6> is OK, only if the original document used them.
Don't change font family. Monospaced tags <pre> and <code> is OK.
Don't use CSS styles margin and padding
Don't use l as a symbol. Use ℓ (mathjax \ell).
Don't write listings as 1., or - . Use <ul> and <ol>.
Use <pre> (block) and <code> (inline) for texts directly related to input and output formats. e.g. Don't use Print "a" but Print "<code>a</code>".
Don't insert whitespaces right after opening parentheses and before closing parentheses. e.g. Don't use ( 1 ≤ N ) but (1 ≤ N).
Insert a space before a parenthesis for a range of some values. e.g. Don't use N(1 ≤ N ≤ 100) but N (1 ≤ N ≤ 100).
Use proper digit group separators. If the number has four digits, you don't need to use them. From five digits, you must use them. Over eleven digits, consider exponential notation. As to what character to use, refer to the following rules.

If you use HTML math expression

Don't use symbols like <=, >=, *, !=, etc. Use mathematical symbols like ≤, ≥, ×, ≠, etc. Refer to Unicode Table.
Use digit group separator ,. Don't use 1 000 000 or 1.000.000 but 1,000,000.
Don't use ^ and _ for superscript and subscript, respectively. Use <sup> and <sub>. e.g. Don't use 10^3 but 10<sup>3</sup>.
Insert whitespaces before and after mathematical symbols. e.g. Don't use a+b but a + b.

Use digit group separator \,. Don't use 1 000 000, 1.000.000, or 1,000,000 but 1\,000\,000.
Don't include parentheses for a range of some values in mathjax. e.g. Don't use $N (1 \le N \le 100)$ but $N$ ($1 \le N \le 100$).