() and "Into the Heart" are the third and fourth tracks, respectively, from U2's debut album, Boy. The two songs are played together as one, both on the album, and during live performances.
Track running times
On European pressings of Boy, "" runs at a track time of 4:47, and "Into the Heart" runs at 3:28. On North American pressings of the album, "" runs at 6:21, and "Into the Heart" runs at 1:58. This can be easily noted by the visible difference between the two vinyls. However, the tracks together sound identical on both pressings, and also both have a total run time of 8:14. Early compact disc releases combined the two songs into a single track. Due to the track time differences, it is difficult to make an official determination of where one song begins and where one ends (although the band's digital box set The Complete U2 and the 2008 remastered version of Boy standardized the original European pressings' running times). Because of this, both songs are usually considered to
Source: http://en.wikipedia.org/wiki/An Cat Dubh