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'.

Ex Input:
Sentence 1:Although the concept of ' compact city ' was coined by American writers , it has been used more in recent years by European and particularly British planners and academics . Sentence 2:nan

Ex Output:
SINGLE_CONN_START


Ex Input:
Sentence 1:The building was completed in 1970 and AA employees moved in at that point , and it was officially opened by Queen Elizabeth in 1973 . Sentence 2:nan

Ex Output:
SINGLE_S_COORD_ANAPHORA


Ex Input:
Sentence 1:A server becomes a candidate if it receives no communication by the leader over a period called the election timeout , so it assumes there is no acting leader anymore . Sentence 2:nan

Ex Output:

SINGLE_S_COORD_ANAPHORA