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After the capture of Belgrade on Oct. 20 , due to losses the division again went into reserves in the town of Ruma , rebuilding to a strength of 6,000 men by the end of December .
 Belgrade, Ruma
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Belgrade, Ruma