gistfile1.txt

#! /bin/bash

for i in {1..20} 
do
        for j in {1..20}
        do
                echo $((i+j)) $i $j 
        done
done | sort -n | while read sum i j
do
        for lat in {n,s} 
        do
                for lng in {w,e} 
                do
                        wget -c "http://imgs.xkcd.com/clickdrag/${i}${lat}${j}${lng}.png" 
                done
        done
done