Thx toolic

Your solution is exactly the solution I also am using to overcome and it works enough for me.

Before my very first posting I was doing (in a loop):

$word =~ /^(\d)\st=(\S+)/;
next if ($1 == 0);
print "$2\n";
[download]

But in this way, for $word="0", pattern was not matched so previous loop's $1 and $2 was printed. And program functioned incorrectly.

Anyway, now I am doing:

next if(!($word =~ /(\d)\st=(\S+)/));
print "$2\n";
[download]

and it works ok for my task.

I thank you for your replies.