8252
The Ko brothers , now in their 60s , recall their impressions of a visit to the Liao Tianding gravesite : " It must have been 30 years ago , we used to go there just for the fun of it .
 person: Ko; date: 60s; person: Liao Tianding; date: 30 years ago
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: date, organization, person, geographical social political, national religious political, facility, cardinal, location, work of art, law, event, product, ordinal, percent, time, quantity, money, language 
Text: {0} 
Answer:
 person: Ko; date: 60s; person: Liao Tianding; date: 30 years ago