On the September 28 airing of SBS's Chuseok special program called 'CPR Song,' Red Velvet's Wendy and Jung Joon Il harmonized to a long-forgotten song titled "76-70 = (heart)" by singer Seo Ji Won.�

The song's original composer, Park Seon Ju said in an interview, "I composed and wrote this song and even sang it with [Seo Ji Won]. It's about a man and woman who are in an ambiguous relationship."�

"This song has never been sung on stage before. I hope they will sing it with heart because I believe it will make for a fantastic stage and special memories." Through Wendy and Jung Joon Il's vocals, the judging panel and the audience recollected memories of Seo Ji Won, who passed nearly a decade ago.�

SEE ALSO: Seoul Philharmonic Orchestra reveals dramatic MV for Red Velvet's 'Psycho'

'CPR Song' is a special program which revolves around a concept of enjoying artists' songs which are considered hidden gems that didn't make the cut as the album's title tracks.�

Check out their wonderful performance above!