Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Input: Consider Input: Context: Comet ISON, formally known as C/2012 S1, was a sungrazing comet discovered on 21 September 2012 by Vitali Nevski ( , Vitebsk, Belarus) and Artyom Novichonok ( , Kondopoga, Russia). 
 Question: By whom was Comet ISON discovered?

Output: artyom novichonok


Input: Consider Input: Context: At Peikapw, a place of prayer, Isokelekel saw his reflection in a pool of water and, realizing his old age, decided to commit suicide. 
 Question: Was the death of Isokelekel an accident or suicide?

Output: suicide


Input: Consider Input: Context: Rock and roll music developed in the United States in the early nineteen-fifties. It was based on the music called rhythm and blues that was performed by African American musicians. Early rock and roll singers developed their own kinds of music. Elvis Presley, Chuck Berry, the Beach Boys, and Bob Dylan were the most popular rock and roll musicians in the early 1960's. All were American. Then, in 1964, a new rock and roll group from England invaded America: the Beatles. Some people say the Beatles' music shook America like an earthquake. The Beatles changed rock and roll forever. Their early songs were influenced by American rock and roll musicians, including Chuck Berry. But the Beatles looked different and sounded different from any musical group before them. The Beatles released their first album in the United States in 1964, when all of the top five records in America were by the Beatles. In 1967, they released an album called "Sergeant Pepper's Lonely Hearts Club Band." It was one of the first "concept" albums. That is, all the songs were linked by a common story or idea. The popularity of the Beatles led the way for more rock and roll bands from England to become popular in America. The Rolling Stones was the most important of these bands. The Rolling Stones is one of the few groups from the 1960's that is still performing and recording today. In 1965, the group recorded one of its most famous songs, "Satisfaction". The musical instrument most linked to rock and roll is the guitar. Experts say Jimi Hendrix was one of the most influential guitar players in rock and roll during the late 1960's. His "Purple Haze" was liked by many people. By the 1970's, rock and roll music became known as rock music. It expanded into many new forms. For example, there was country rock, hard rock, acid rock, and heavy metal rock. Punk rock, jazz rock, and glitter rock. In the middle 1970's, experts say rock music regained some of the energy of early rock and roll. Bruce Springsteen and the E Street Band became popular with their album "Born to Run". Springsteen's music was like the lively rock and roll music of the early nineteen-sixties. Many of his songs were about social issues. He sang about the effects of unemployment and the war in Vietnam. 
 Question: Whose songs were mainly about social problems like unemployment and war?


Output: springsteen's.