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Rockabilly was most popular with country fans in the 1950 s , and 1956 could be called the year of rockabilly in country music , with Johnny Cash emerging as one of the most popular and enduring representatives of the rockabilly genre ; rockabilly was also a starting point for eventual rock-and-roll superstar Elvis Presley , who would return to his country roots near the end of his life .
 person: Johnny Cash; person: Elvis Presley
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Johnny Cash, Elvis Presley 
Answer:
 person: Johnny Cash; person: Elvis Presley