#! /bin/sed -f
# Laurent Le Brun <laurent [at] le-brun.eu> - 2007

:loop
s/^\(.\)\(.*\)\1$/\2/
t loop
/...*/ {
    i\
 no
    b end
}  
i\
 yes

:end
d  

### colorized by sedsed, a SED script debugger/indenter/tokenizer/HTMLizer
### original script: http://laurent.le-brun.eu/pub/palindrome.sed