sub f{
local$';
local$`;
local@a;
local$s=0;
"@_"=~/(.)(.*)(?!\1)(.)(.*)\3(?{push@a,[$1.$3x2,"$`$2$4$'"]})^/;
#$s+=$-=$$_[0]-$s+f($$_[1])for@a;
#$s<($x=$$_[0]+f($$_[1]))&&($s=$x)for@a;
$s<($x=$$_[0]+0+f($$_[1].''))&&($s=$x)for@a;
$s;
}
#print f<>
$_=<>;chomp;print f$_