use strict;
use warnings;

my @dir;
my @filelist;
open OUT, ">result.fst";
opendir (DIR, "./") or die "can't open the directory!";
@dir = readdir DIR;
foreach my $file (@dir) {
    if ( $file =~ /[a-z]*\.seq/) {
        push @filelist,$file;
    } 
}
closedir(DIR);

foreach my $file (@filelist
 
){
    open IN, "<".$file or die "cannot open $file";
    print OUT ">".$file."\n";
    print OUT <IN>;
    close(IN);
}

close (OUT);