10484
Nicaragua 's Defense Ministry said a group of Contra rebels ambushed two trucks carrying troops in northern Nicaragua , killing 18 of the soldiers .
 Nicaragua, Defense Ministry, Contra, two, Nicaragua, 18
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: date, organization, person, geographical social political, national religious political, facility, cardinal, location, work of art, law, event, product, ordinal, percent, time, quantity, money, language 
Text: {0} 
Answer:
 Nicaragua, Defense Ministry, Contra, two, Nicaragua, 18