$ perl -le' $_ = join "+", 1 .. 10; print; s/\+(\d+(?:\+|$))/-$1/g; pr
+int; print eval'
1+2+3+4+5+6+7+8+9+10
1-2+3-4+5-6+7-8+9-10
-5

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In reply to Re: stupid question about switching signs every number by jwkrahn
in thread stupid question about switching signs every number by derpp

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