use strict;

my $a="123-135, 1-119, 1270-1280, 1420-1452";
print "Original : $a\n";

my @a = split (/\, /, $a);
eval{s/^([0-9]*)([0-9]+)\-([0-9]*)([0-9]+)$/&digit($1,$2,$3,$4)/egsi;} for (@a);

print "Changed  : ";
print "$_\t" for @a;

sub digit{
    my ($f, $f1, $s, $s1)=@_;
my ($fs, $se);
    if($s =~ /([0-9]+)([0-9])/)
   {
	    $fs = $1; $se = $2;
   }
    if ($f == $s)
    {
        $s=$s1;
    }
    elsif($f=~/^$fs/)
    {
	    $s=$se.$s1;
    }
	    
    else{
        $s=~s/\d//; $s.=$s1;
    }        
return qq($f$f1-$s);
}