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:It has become an ongoing tradition that the Pelican editor appears naked on the front cover of the final edition , although it is unknown when this tradition began . Sentence 2:nan

Ex Output:
SINGLE_CONN_INNER


Ex Input:
Sentence 1:Using four mysterious stones , they begin to pray which begins to call Landorus at its designated monument . Sentence 2:nan

Ex Output:
SINGLE_CATAPHORA


Ex Input:
Sentence 1:Retrieved January 28 , 2015 . Sentence 2:The flag of the Commonwealth shall be a deep blue field , with a circular white centre of the same material .

Ex Output:

PAIR_NONE