Background: Rouvas was born on 5 January 1972 in the village of Mandoukion, near Corfu City on the island of Corfu, the eldest of four sons of Konstantinos "Kostas" Rouvas (an ambulance driver) and the teenaged Anna-Maria Panaretou (a duty-free shop clerk at the local airport). He has three brothers: Billy (b. Vasilios), Tolis (b. Apostolos, 1975) and Nikos (b. Nikolaos, 1991). The family was poor, and Rouvas began taking care of his brothers at age five. At age four, he exhibited athletic ability and took ballet classes as a child.
Context: In December 1998 Rouvas released his sixth album (the first with his new label): Kati Apo Mena (Something From Me), written by Giorgos Theofanous. "Den Ehi Sidera I Kardia Sou" ("Your Heart Doesn't Have Steel Rails") was a hit, and remains one of his most-popular songs. To promote the album Rouvas performed at the Virgin Megastore in Athens, where thousands of fans created a traffic jam. The next year, Rouvas records "Oso Exo Esena" ("As Long As I Have You"), a duet with singer Stelios Rokkos. The two artists work and perform together at Bio Bio in Athens during the summer.  In March 2000 Rouvas released his seventh album, 21os Akatallilos (21+ X-Rated), and performed with Katy Garbi at Pili Axiou in Thessaloniki. The album and its first single, "Andexa" ("I Held Out"), reached number one on the charts. During May rehearsals for summer performances Rouvas was hospitalized with abdominal pain, which was diagnosed as peritonitis and required an appendectomy. On 25 October 2000, he began appearing with Antonis Remos and Peggy Zina at Apollonas for the winter season. That year Rouvas became the Pepsi spokesperson for the company's Greek summer campaign making a first television ad, a first for a Greek entertainer. His collaboration with Pepsi continued into 2001, with a May television ad. The advertisement, featuring a semi-nude Rouvas holding a Pepsi bottle in front of his genitals, was controversial among women's rights and parental associations. Calling it "unsightly, vulgar and unacceptable", they tried to have the ad blocked as "disgrac[ing] childhood innocence and dignity." The Pepsi Tour 2001, of seven Greek cities, followed.  During summer 2000 Rouvas, Psinakis and a number of other celebrities visited Mykonos on a yacht borrowed from a local physician. They were accused of drug possession, since the yacht contained narcotics. The incident was publicized amid speculation that Rouvas might have a drug addiction. Although the doctor admitted that the narcotics were his, his guests were questioned. Wishing to avoid court, Rouvas paid a fine and minimized the incident. However, thousands of T-shirts were printed which read: "Imoun ki ego sto kotero!" ("I was on the yacht, too!").
Question: what kind of drugs did the yacht have on it?
Answer: narcotics

Problem: Background: Georg Ferdinand Ludwig Philipp Cantor ( KAN-tor; German: ['geoRk 'feRdinant 'lu:tvIc 'fIlIp 'kantoR]; March 3 [O.S. February 19] 1845 - January 6, 1918) was a German mathematician. He invented set theory, which has become a fundamental theory in mathematics. Cantor established the importance of one-to-one correspondence between the members of two sets, defined infinite and well-ordered sets, and proved that the real numbers are more numerous than the natural numbers.
Context: Cantor's 1874 Crelle paper was the first to invoke the notion of a 1-to-1 correspondence, though he did not use that phrase. He then began looking for a 1-to-1 correspondence between the points of the unit square and the points of a unit line segment. In an 1877 letter to Richard Dedekind, Cantor proved a far stronger result: for any positive integer n, there exists a 1-to-1 correspondence between the points on the unit line segment and all of the points in an n-dimensional space. About this discovery Cantor wrote to Dedekind: "Je le vois, mais je ne le crois pas!" ("I see it, but I don't believe it!") The result that he found so astonishing has implications for geometry and the notion of dimension.  In 1878, Cantor submitted another paper to Crelle's Journal, in which he defined precisely the concept of a 1-to-1 correspondence and introduced the notion of "power" (a term he took from Jakob Steiner) or "equivalence" of sets: two sets are equivalent (have the same power) if there exists a 1-to-1 correspondence between them. Cantor defined countable sets (or denumerable sets) as sets which can be put into a 1-to-1 correspondence with the natural numbers, and proved that the rational numbers are denumerable. He also proved that n-dimensional Euclidean space Rn has the same power as the real numbers R, as does a countably infinite product of copies of R. While he made free use of countability as a concept, he did not write the word "countable" until 1883. Cantor also discussed his thinking about dimension, stressing that his mapping between the unit interval and the unit square was not a continuous one.  This paper displeased Kronecker, and Cantor wanted to withdraw it; however, Dedekind persuaded him not to do so and Weierstrass supported its publication. Nevertheless, Cantor never again submitted anything to Crelle.
Question: Was his work in this field unique?
Answer: