21423
" Telephone-switching networks " of electromechanical relays ( invented 1835 ) was behind the work of George Stibitz ( 1937 ) , the inventor of the digital adding device .
 person: George Stibitz
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: George Stibitz 
Answer:
 person: George Stibitz