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'.

Example 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
Example Output: SINGLE_CONN_START

Example Input: Sentence 1:Agriculture and trade flourished in these centuries , and Piacenza became one of the richest cities in Europe . Sentence 2:nan
Example Output: SINGLE_S_COORD

Example Input: Sentence 1:macrorhynchus quota plan : This subspecies , which is relatively abundant in the territory 's northern part , was thought plentiful enough to sustain limited harvesting of young for commercial purposes . Sentence 2:nan
Example Output:
SINGLE_RELATIVE