Perl One Liners

% echo "1\n2\n-5" | perl -ne '$n += $_; END { print "$n\n" }'
-2

% echo "1 3\n2 4\n-5 -3" | perl -ane '$n+=$F[0]; END { print "$n\n" }'
-2

% echo "1 3\n2 4\n-5 -3" | perl -ane '$n+=$F[1]; END { print "$n\n" }'
4