Before: $$(31-1-18) \div 2 = 6$$, and John: $$6+1=7$$. 
There were $$31$$ runners competing in a race. The number of runners who finished before John is $18$ less than the number of runners who finished later than John. At what place did John finish? (Adapted from 1998 Math Kangaroo Problem, Level 3 - 4, Question \#13) 
Options:
[A] $$6$$ 
[B] $$7$$ 
[C] $$8$$ 
[D] $$20$$ 
[E] $$21$$ 