Play The Harp

This was kinda guessy imo but anyway

strings harp.jpg | less

then i scrolled loads hoping i would see something good and found a long list of chars:

HDNR6GFf
6LLIJK9l
18NL1HWa
GCU85U5g
RQ9CGTH{
T47Y9SUt
2SKZJOBh
H06K09Ze
3BWV54X_
C1VY4EIh
GO0DK9Ua
ZZLVBMZr
8CK8FTGp
TNDQURH_
CEHGS41i

like this but longer, looking at the last char we assemble the flag together

flag: flag{the_harp_instrument_has_vertical_strings}