N :0 s/\<\(\w*\)\>\(.*\)\<\1\>/\2/ t0 s/$/@ abcdefghijklmnopqrstuvwxyz/ : s/\<\(\(.\)\w*\)\s\+\(\(\w\)\w*\)\>\(.*@.*\4.*\2\)/\3 \1\5/ t s/\<\(\(\w*\)\(\w\)\w*\) \(\2\(.\)\w*\)\(.*@.*\5.*\3\)/\4 \1\6/ t s/@.*//
Note that non-ascii characters in the above source code will be escaped (such as \x9f).