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/@.*//