Question: How many episodes are in the 2014 American documentary about a band who's frontman is Dave Grohl?

full_context: Document 1: Classic Albums: Nirvana – Nevermind: Classic Albums: Nirvana – Nevermind is a documentary DVD released by Eagle Vision in March 2005, as part of the "Classic Albums" series. It features interviews specifically for this release with Nirvana band members Dave Grohl and Krist Novoselic, as well as "Nevermind" album producer Butch Vig about the recording of the album. Other interview highlights include Garry Gersh (A&R DGC Records), Jonathan Ponneman and Nils Bernstein (Sub Pop Records), Thurston Moore (Sonic Youth) and Jack Endino.
Document 2: America's Music: The Roots of Country: America's Music: The Roots of Country is a 1996 three-part, six episode documentary about the history of American country music directed by Tom Neff and Jerry Aronson and written by Neff and Robert K. Oermann. The film touches on many of the styles of music that make up country music, including: Old-time music, Cajun music, Folk music, Rockabilly, Western music, Western swing, the Bakersfield sound, Honky-tonk and the Nashville sound. Country music artist and actor Kris Kristofferson narrates the three-part series.
Document 3: Dave Foster: Dave Foster is an American musician who was the third drummer for the grunge rock band Nirvana. He was fired after playing only a couple of performances with the band, mostly because of his inability to attend rehearsal sessions regularly. Foster lived hours away from Kurt Cobain and bassist Krist Novoselic back in Aberdeen, Washington, which required the men to pick Foster up and bring him to the band's rehearsal space in Tacoma. Based on Cobain's own account, this made band practices complicated.
Document 4: Foo Fighters: Sonic Highways: Sonic Highways is a 2014 American documentary miniseries directed by Dave Grohl and written by Mark Monroe. The documentary was made concurrently with Foo Fighters' eighth album, "Sonic Highways", and was broadcast on HBO. Grohl described the project as "a love letter to the history of American music". Each of the eight episodes is presented as an exploration of the musical history of a different American city through a series of interviews by Grohl. The group is also shown incorporating what they learned from the interviews into the writing and recording of a new song in or near that city. The series debuted on October 17, 2014.
Document 5: List of songs recorded by Nirvana: Nirvana was an American rock band formed by singer/guitarist Kurt Cobain and bassist Krist Novoselic in Aberdeen, Washington in 1987, with drummer Dave Grohl joining the band in 1990. Though their brief run ended following the death of Kurt Cobain in 1994, Nirvana has come to be regarded as one of the most influential and important rock bands of the modern era.
Document 6: Foo Fighters discography: The discography of Foo Fighters, an American rock band formed in 1994 by Dave Grohl, consists of nine studio albums, four extended plays (EPs), six video albums, and 36 singles. The current Foo Fighters line-up consists of Grohl (vocals and guitar), Taylor Hawkins (drums), Rami Jaffee (keyboard), Nate Mendel (bass), Chris Shiflett (guitar), and Pat Smear (guitar).
Document 7: In Your Honor: In Your Honor is the fifth studio album by American rock band Foo Fighters, released on June 14, 2005 by RCA Records. It is a double album, with one disc containing heavy rock songs and a second disc with mellower acoustic songs. Frontman Dave Grohl decided to do a diverse blend of songs as he felt that after ten years of existence, the band had to break new ground with their music. The album was recorded at a newly built studio in Northridge, Los Angeles, and featured guests such as John Paul Jones, Norah Jones and Josh Homme. The lyrics deal with both resonating and introspective themes, with a major influence from Grohl's involvement on the campaign trail with John Kerry during the 2004 presidential election.
Document 8: Dave Grohl: David Eric Grohl (born January 14, 1969) is an American rock musician, guitarist, singer, drummer, songwriter, record producer, and film director. He is the former drummer of the grunge band Nirvana and the frontman and founder of the rock band Foo Fighters, of which he is the lead vocalist, rhythm and lead guitarist, and primary songwriter.
Document 9: Foo Fighters (album): Foo Fighters is the self-titled debut studio album by American hard rock band Foo Fighters, released on July 4, 1995, by Capitol Records through Dave Grohl's label Roswell. Grohl wrote and recorded the entire album himself – with the exception of a guest guitar spot by Greg Dulli – with the assistance of producer Barrett Jones at Robert Lang Studios in Seattle, Washington, in 1994. Grohl claimed he recorded the album just for fun, describing it as a cathartic experience to recover from the death of his Nirvana lead singer Kurt Cobain.
Document 10: Nirvana (band): Nirvana was an American rock band formed by singer and guitarist Kurt Cobain and bassist Krist Novoselic in Aberdeen, Washington, in 1987. Nirvana went through a succession of drummers, the longest-lasting being Dave Grohl, who joined in 1990. Despite releasing only three full-length studio albums in their seven-year career, Nirvana has come to be regarded as one of the most influential and important alternative bands in history. Though the band dissolved in 1994 after the death of Cobain, their music maintains a popular following and continues to influence modern rock and roll culture.
Document 11: Probot: Probot was a heavy metal side project of ex-Nirvana drummer and Foo Fighters rhythm guitarist and lead-singer Dave Grohl. Described by Grohl as "a death metal "Supernatural,"" the album mixes instrumentals recorded by Grohl himself with various metal singers whom the musician admired. The album was released in February 2004 by Southern Lord Records. It featured one single entitled "Centuries of Sin"/"The Emerald Law".
Document 12: Gigantic (A Tale of Two Johns): Gigantic (A Tale of Two Johns) is a documentary profiling the alternative rock band They Might Be Giants, featuring interviews with Frank Black, Sarah Vowell, Dave Eggers, Jon Stewart, and others. It was directed by AJ Schnack and premiered at the South by Southwest Film Festival in 2002. It was released in theaters by Cowboy Pictures, and on DVD by Plexifilm in 2003. The DVD includes bonus features such as music videos, vintage live performances, and more.
Document 13: Mantra (Dave Grohl song): "Mantra" is a song by Dave Grohl, Josh Homme, and Trent Reznor from the 2013 album "", the soundtrack to the 2013 documentary "Sound City". Grohl was joined by different artists for different tracks as Grohl's Sound City Players. For "Mantra", the final track on the album, he was joined by Homme and Reznor. Homme also appeared on two other tracks on the album, "Centipede" and "A Trick With No Sleeve".
Document 14: Foo Fighters: Foo Fighters is an American rock band, formed in Seattle, Washington in 1994. It was founded by Nirvana drummer Dave Grohl as a one-man project following the dissolution of Nirvana after the death of Kurt Cobain. The group got its name from the UFOs and various aerial phenomena that were reported by Allied aircraft pilots in World War II, which were known collectively as "foo fighters".
Document 15: List of Foo Fighters band members: Foo Fighters is an American alternative rock band formed by multi-instrumentalist and vocalist Dave Grohl in 1994. After recording the album "Foo Fighters" alone, Grohl enlisted guitarist Pat Smear, bassist Nate Mendel and drummer William Goldsmith to join the band. This lineup recorded the second Foo Fighters album, 1997's "The Colour and the Shape", although most of Goldsmith's drum recordings were removed and re-recorded by Grohl for the release, after he left the band due to creative tensions. Goldsmith was replaced by Taylor Hawkins, and Franz Stahl replaced Smear after he also departed, although he only remained in the band for a short period and did not record an album with the group. The group's third album, "There Is Nothing Left to Lose", featured Hawkins on drums and was released in 1999.
ground_truth: eight