Given the Target and Argument texts detect the stance that the argument has towards the topic. There are three types of stances "in favor", "against", and "neutral". 

Topic: Needle exchanges
 Argument: Needle exchanges protect public, not just drug addicts.
in favor

Topic: Banning vuvuzela horns at the 2010 World Cup
 Argument: Guests at World Cup should embrace S. African vuvuzela tradition.
against

Topic: Manned mission to Mars
 Argument: Cumulative challenges and risks of Mars mission are too great.

against