#!perl
use strict;
my $Number = '  5 4 1  321 0 698 7 3  210 2 0   0';
my @Number = split //,$Number;
my $count = 0;
for my $i (0..$#Number){
  next if ($Number[$i] =~ /\D/);
  if (($count > 5) && ($count < 14)){
    $Number[$i] = "X";
  }
  ++$count;
}
print join '',@Number;