Problem: Background: The Vienna Boys' Choir (German: Wiener Sangerknaben) or Vienna Choir Boys is a choir of boy sopranos and altos based in Vienna, Austria. It is one of the best known boys' choirs in the world. The boys are selected mainly from Austria, but also from many other countries. The choir is a private, not-for-profit organization.
Context: The choir is the modern-day descendant of the boys' choirs of the Viennese Court, dating back to the late Middle Ages. The choir was, for practical purposes, established by a letter from Emperor Maximilian I of Habsburg on 30 June 1498, instructing court officials to employ a singing master, two basses and six boys. Jurij Slatkonja became the director of the ensemble. The role of the choir (numbering between 24 and 26) was to provide musical accompaniment for the church mass. Additionally, the Haydn brothers were members of the St. Stephen's Cathedral choir, directed at the time by Georg Reutter II, who used this choir in his duties for the imperial court, which at the time had no boy choristers of its own.  Over the centuries, the choir has worked with many composers, including Heinrich Isaac, Hofhaimer, Biber, Fux, Caldara, Gluck, Salieri, Mozart, Franz Schubert and Bruckner.  In 1920, following the fall of the Austrian Empire, the Hofkapelle (court orchestra) was disbanded. However, the rector at the time, Josef Schnitt, sought a continuation of the tradition. In 1924, the Vienna Boys' Choir was officially founded, and it has evolved into a professional music group. The choir adopted the now-famous blue and white sailor suit, replacing the imperial military cadet uniform that included a dagger. The composer HK Gruber is one of the graduates of the reformed choir.  Since 1948, the Palais Augarten has served as their rehearsal venue and boarding school, which goes from kindergarten level up to middle school level.  In 1961, Walt Disney filmed Almost Angels, a fictional drama about (and starring) the Vienna Boys' Choir, set and filmed in the Palais Augarten. It was Disney who, for cinematographic reasons, persuaded the Austrian government to allow the boys to legally wear the Austrian national emblem on the breast of their uniform, a tradition that continues to this day.
Question: What happened with the Vienna Boys' Choir in early history?
Answer: The role of the choir (numbering between 24 and 26) was to provide musical accompaniment for the church mass.

Problem: Background: David Michael Letterman (born April 12, 1947) is an American television host, comedian, writer, and producer. He hosted a late night television talk show for 33 years, beginning with the February 1, 1982, debut of Late Night with David Letterman on NBC, and ending with the May 20, 2015, broadcast of Late Show with David Letterman on CBS. In total, Letterman hosted 6,028 episodes of Late Night and Late Show, surpassing friend and mentor Johnny Carson as the longest-serving late night talk show host in American television history. In 1996 Letterman was ranked 45th on TV Guide's 50 Greatest TV Stars of All Time.
Context: In 1975, encouraged by his then-wife Michelle and several of his Sigma Chi fraternity brothers, Letterman moved to Los Angeles, with hope of becoming a comedy writer. He and Michelle packed their belongings in his pickup truck and headed west. As of 2012, he still owned the truck. In Los Angeles, he began performing comedy at The Comedy Store. Jimmie Walker saw him on stage; with an endorsement from George Miller, Letterman joined a group of comedians whom Walker hired to write jokes for his stand-up act, a group that at various times would also include Jay Leno, Paul Mooney, Robert Schimmel, Richard Jeni, Louie Anderson, Elayne Boosler, Byron Allen, Jack Handey, and Steve Oedekerk.  By the summer of 1977, Letterman was a writer and regular on the six-week summer series The Starland Vocal Band Show, broadcast on CBS. He hosted a 1977 pilot for a game show entitled The Riddlers (that was never picked up), and co-starred in the Barry Levinson-produced comedy special Peeping Times that aired in January 1978. Later that year, Letterman was a cast member on Mary Tyler Moore's variety show, Mary. Letterman made a guest appearance on Mork & Mindy (as a parody of EST leader Werner Erhard) and appearances on game shows such as The $20,000 Pyramid, The Gong Show, Hollywood Squares, Password Plus and Liar's Club, as well as the Canadian cooking show Celebrity Cooks (November 1977), talk shows such as 90 Minutes Live (February 24 and April 14, 1978), and The Mike Douglas Show (April 3, 1979 and February 7, 1980). He was also screen tested for the lead role in the 1980 film Airplane!, a role that eventually went to Robert Hays.  His dry, sarcastic humor caught the attention of scouts for The Tonight Show Starring Johnny Carson, and Letterman was soon a regular guest on the show. Letterman became a favorite of Carson and was a regular guest host for the show beginning in 1978. Letterman credits Carson as the person who influenced his career the most.
Question: When did he move to LA?
Answer: In 1975, encouraged by his then-wife Michelle and several of his Sigma Chi fraternity brothers, Letterman moved to Los Angeles,

Problem: Background: Eunhyuk was born Lee Hyuk-jae in Seoul, South Korea. He has an older sister Lee So-ra. Raised in a family that struggled financially, he was interested in street performing as a child. Inspired by the likes of H.O.T's Jang Woo-hyuk, Michael Jackson and singer-dancer Yoo Seung-jun, Eunhyuk trained himself at a young age.
Context: On 26 February 2010, Eunhyuk was diagnosed with H1N1 influenza, but was set to appear as a guest at label mate Girls' Generation's Into the New World encore concert in Seoul, hence had to pull out and was replaced by bandmates Leeteuk and Heechul. Super Junior released their 4th studio album, Bonamana, with similar success in Korea, sweeping awards in music programs after the release date. Their follow-up song, Boom Boom, was choreographed by Eunhyuk and performed on music programs Inkigayo and Music Core. On October 8, 2010, the digital single 'Angel' for HARU OST was released, with Eunhyuk featuring a rap verse.  In 2011, Eunhyuk, along with Sungmin was placed two new members of Super Junior-M. On 27 September 2011, he along with Yesung and Shindong filled in for bandmate Heechul, who enlisted for mandatory military service on 1 September, during the performance on Music Bank and Show! Music Core of Kim Jang-hoon latest single, "Breakups are So Like Me". Heechul is featured in the song and starred in the music video, which was completed the day before he enlisted. Mr. Simple, Super Junior's award-winning 5th studio album, was promoted heavily with Eunhyuk participating in much of the album's production through choreography, and rap lyrics for the track, Oops. The album sold over 500,000 units and won the Disk Daesang Award at the 26th Golden Disk Awards and 21st Seoul Music Awards, as well as Album of the year at the 13th Mnet Asian Music Awards. The album is listed as the 2nd best-selling album as of the year 2011.  In November, Eunhyuk made his musical theatre debut in Fame, where he played Tyrone Jackson, along with Tiffany of Girls' Generation, Son Ho Young, Lina of The Grace and Kim Jung Mo of TRAX. It was on at the Woori Financial Art Hall from 25 November 2011 to 29 January 2012. It was announced on 30 November 2011 that after five years, he and Leeteuk would leave Super Junior's Kiss the Radio and was replaced by fellow members, Sungmin and Ryeowook on 4 December 2011.
Question: Who is Mr. Simple?
Answer:
Super Junior's award-winning 5th studio album,