guests has columns guest_id, nationality, gender and age.
Add a rank column where the oldest guest ranks 1. Guests of the same age share
a rank and the ranks after a tie are skipped, so two guests tied at 1 are
followed by rank 3. Return all the original columns plus rank, sorted by
rank then guest_id, with the index renumbered from 0.
Input
guest_id nationality gender age
0 1 FR f 41
1 2 DE m 55
2 3 IT f 55
3 4 ES m 30
Output
guest_id nationality gender age rank
0 2 DE m 55 1
1 3 IT f 55 1
2 1 FR f 41 3
3 4 ES m 30 4