69060
They became friends in the summer of 1980 , and kept in touch until , some twenty-three years later , they finally began to cooperate on their writing .
 None
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:  
Answer:
 None