p143: rename some (p,q,r) to (i,j,k).
p143: rename some (p,q,r) to (i,j,k).

as the previous name is confusing because
p,q,r in the problem description not refering to the same thing,
and this is also why I mis-calculated the bound for m previously.

Javran/Project-Euler,Javran/Project-Euler