#sub conv{
#	my@n=$_[0]=~/./g;
#	("`"x$#n).join"",map".".$_,@n
#}
#@L=("+","-");
#$n=4;
#sub f{
#	my($i,$a,$s)=@_;
#	if($i==$n){
#		print"`r\n";
#		for$b(@L){
#			f($i-1,$b,$b);
#		}
#		print"i\n";
#	}
#	elsif($i>0){
#		print"\t"x($n-$i-1),"```?$a".($a eq$L[0]?"`@":"")."i`d\n";
#		for$b(@L){
#			f($i-1,$b,$s.$b);
#		}
#		print"\t"x($n-$i),"i\n";
#	}
#	else
#	{
#		$ans=($s=~y/+//)-($s=~y/-//);
#		print"\t"x($n-$i-1),"```?$a".($a eq$L[0]?"@`":"")."i`d".conv($ans).$/;
#	}
#}
#f($n);
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