Tags arrive as one comma-separated string per article, typed by hand. The warehouse wants them as a bridge table.

Input

Output

One row per article and tag, with the columns article_id and tag.

• Split on commas, then trim each tag.
• Drop anything that is empty once trimmed.
• The same tag twice on one article is one row.
• An article with no usable tag contributes no rows at all.

Example

Constraints

• Trim after splitting. Only the split knows where each tag begins.
• Case is content. Delta, delta and DELTA are three different tags.
• Row order is not graded. Column names and their order are.