instruction:
In this task, you are given two sentences in the English language and your task is to classify them into one of their discourse types. A discourse type is an indicator to classify the given two sentences on the basis of a co-text as well as a relevant context. There are 13 discourse types in total which are 'SINGLE_S_COORD', 'SINGLE_CATAPHORA', 'SINGLE_CONN_INNER', 'SINGLE_APPOSITION', 'SINGLE_VP_COORD', 'SINGLE_CONN_START', 'PAIR_ANAPHORA', 'PAIR_CONN', 'SINGLE_RELATIVE', 'SINGLE_CONN_INNER_ANAPHORA', 'SINGLE_S_COORD_ANAPHORA', 'PAIR_CONN_ANAPHORA' and 'PAIR_NONE'.
question:
Sentence 1:It is the most historic area of Derby , the location of a large fortified Roman settlement , which they called Derventio . Sentence 2:nan
answer:
SINGLE_APPOSITION


question:
Sentence 1:The YouTube app , which had been a default app on iOS developed by Apple , was removed . Sentence 2:nan
answer:
SINGLE_RELATIVE


question:
Sentence 1:After they opened the ground , they set up a perimeter using ropes because of a lack of money . Sentence 2:Then , with hard economising , they bought a horizontal bar and other gymnastic equipment .
answer:

PAIR_CONN