Confident (album) move on and be happy with someone else. The song incorporates pop and soul influences, and is centered on a piano melody, with a stripped down production aimed at highlighting Lovato's vocals. "Stone Cold" received comparisons to Lovato's 2011 song "Skyscraper" and the work of English singer Adele. The album follow with the trap-inspired song "Kingdom Come" it features vocal appearance by rapper Iggy Azalea. Several critics noted that the song is comparable to Azelea's "Black Widow" (2014) featuring Rita Ora. "Waitin for You" featuring vocals by singer Sirah, musically, it's an R&B and hip hop song that starts with
Pretty Girls (Britney Spears and Iggy Azalea song) album. When asked who she would like to collaborate with, Spears said she would like to do something with Katy Perry or Iggy Azalea. Rumors began to circulate that a collaboration between the two artists was already in the works, with Azalea saying she had done a "secret collaboration" with someone she had been interested in. In December 2014, Azalea told Kiss 108 backstage at their Jingle Ball Tour 2014 that their collaborative song would premiere in 2015, "We have a song, which is going to be her first single, coming out next year." Asked how the collaboration came about,