Editorial for Another Contest 6 Problem 6 - Name That Song
Submitting an official solution before solving the problem yourself is a bannable offence.
This problem is a pure song identification problem. The expected solve path for the problem for someone with no background on the problem setter involves identifying some songs that should be guessable or identifiable via Google (indices -5, -4, -3, -1, 4, 8, 9, 13, 15, 18, 20, and 22 are plausible candidates).
After identifying enough of these songs, it should be apparent that the songs are given in alphabetic order, also motivated by indices being negative and index 0 being relatively early in the alphabet.
From this point, the main way to progress further is to identify song 6, and use that to identify the universe of possible songs.