products has columns product, category and revenue.

Within each category, return the products sitting in the top three dense ranks by revenue, so ties do not consume a rank and a category can return more than three rows. Keep the original columns, sort by category then revenue descending then product, and renumber the index from 0.

Input

  product category  revenue
0       a        X     12.0
1       b        X     10.0
2       c        X      9.0
3       d        X      9.0
4       e        X      1.0
5       f        Y      5.0
6       g        Y      4.0
7       h        Y      3.0

Output

  product category  revenue
0       a        X     12.0
1       b        X     10.0
2       c        X      9.0
3       d        X      9.0
4       f        Y      5.0
5       g        Y      4.0
6       h        Y      3.0