($N,$M)=glob<>;
@D=sort{$a-$b}<>;
$\=9e9;
for(0..$M-$N){
	$\-=$-=$\-(($D[$_+$N-1]-$D[$_])+abs$D[$_+$N-1]);
	$\-=$-=$\-(($D[$_+$N-1]-$D[$_])+abs$D[$_]);
}
print