1398
Since hostile mortars moved frequently to avoid return fire it was essential to have a means of locating them to a few tens of metres of accuracy and to be able to respond quickly when they are located .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None