#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11165274
use warnings;

print binary2decimal( 1 . 0 x 8192 ), "\n";

sub binary2decimal
  {
  my $n = 0;
  $n = (0 . $n =~ tr/1-9/246802468/r | $n =~ tr/1-9/00001/r . $_) =~
    s/^0+(?=.)//r for split //, shift;
  return $n;
  }