Songs originated from and were inspired by a variety of sources. "Zooropa" was the result of combining two separate pieces of music together, one of which the band discovered while reviewing recordings of tour soundchecks. The verse melody to "Stay (Faraway, So Close!)" and an instrumental backing track that became "Numb" were originally from the "Achtung Baby" sessions. "Babyface", "Dirty Day", "Lemon", and "The Wanderer" were written during the "Zooropa" sessions. Country singer Johnny Cash recorded vocals for "The Wanderer" during a visit to Dublin, and although Bono recorded his own vocals for the song, he preferred Cash's version. The production crew and the band debated which version to include on the record. Throughout the sessions, U2 were undecided on a unifying musical style for the release, and as a result, they maintained three potential track listings—one for the best songs, one for "vibes", and one for a soundtrack album. Bono suggested editing the best segments of songs together to create a montage.