Task: Question Answering
Input (English): Passage: To promote No Line on the Horizon, U2 performed "Get on Your Boots" at the 51st Grammy Awards, the 2009 BRIT Awards, and the 2009 Echo Awards, although the album was not eligible for awards at any of the ceremonies. The band later appeared on French television and radio on 23 February 2009, and on 26 February they taped a segment for Friday Night with Jonathan Ross, which was aired the next day. On 27 February, U2 made an appearance on a Live Lounge session for BBC Radio 1, followed by a mini-concert on the roof of Broadcasting House. On the week of 2 March 2009, U2 appeared on CBS-TV's Late Show with David Letterman for five consecutive nights, the first time a musical guest had performed for an entire week on the show. The group performed "Breathe", "Magnificent", "I'll Go Crazy If I Don't Go Crazy Tonight", "Beautiful Day", and "Get on Your Boots". On 3 March, Michael Bloomberg, Mayor of New York City, added a street sign reading "U2 Way" at 53rd Street in Manhattan, for the week that U2 performed on the Late Show. U2 also performed at Fordham University on 6 March 2009 for an appearance on ABC-TV's Good Morning America. From 9 to 11 March, the band participated in "U2 3 Nights Live", a series of radio interviews and performances that were broadcast across North America and streamed live on U2.com.From 11 to 17 February 2009, U2.com hosted a promotion where 4,000 fans could win a 7-inch single collector's edition box set that contained all four of the singles released from No Line on the Horizon. An alternate version of the title track, "No Line on the Horizon 2", debuted on RTÉ 2XM on 12 February 2009; it was later used as the B-side for the first single, "Get on Your Boots". The full album began streaming on the group's MySpace page on 20 February 2009, and on U2.com a few days later.Four singles were planned from the album, although only three were released. The first single, "Get on Your Boots", was released as a digital download on 19 January 2009, and in a physical format on 16 February 2009. The iTunes store held the exclusive digital download rights to the single for the first 24 hours. The second single, "Magnificent", was released on 4 May 2009. The third single, "I'll Go Crazy If I Don't Go Crazy Tonight", was released on 7 September 2009. 
Question: What was later used as the B-side for the first single?
Output (English): "No Line on the Horizon 2".