use strict;
use warnings;

my $x=123;
use constant LENGTH=>5;
use constant LOG10=>2.30258509299405;
$_ = $x;
if(s/.//){s/./0/g; s/^/1/;}

my $shorth= int(1.5+&Log() / LOG10);
my $shorth2=int(1.5+ log() / LOG10);
if($shorth != $shorth2) {die "logirithmical error";}
die "too long" if $shorth > LENGTH;
$x = 0 x (LENGTH-$shorth) . $x;
print "$x\n";

sub Log{
  my($r)=@_ ? @_ : ($_);
  if(abs($r)>=1){
    return -&Log(1/$r);
  }
  $r-=1;
  my $sign=1;
  my $ret=0;
  my $f=1;
  for my $n (1..40){
    $f*=$r;
    $ret+=$sign*$f/$n;
    $sign=-$sign;
  }
  return $ret;
}