#!/usr/bin/perl
# The first line might be #!/usr/local/bin/perl etc 
# depending on the system.
#
# Do not delete this comment.#####################

if ( $#ARGV < 0 ) { 
	print "usage: $0 ptable\n";
	print "Makes prefix from *.p.table.\n";
	exit 1;
}

$infile = $ARGV[0];
$outfile = "prefix";
$| = 1;
print "input file is $infile.\n";

open(INFILE, $infile) || die "Unable to open file: $infile.\n";
open(OUT, ">$outfile") || die "Unable to open output file: $outfile.\n";

@A = ( );
$max = 0;

while(<INFILE>) {
	$line = $_;
	@linelist = split(/\t/, $line);
	$ID = $linelist[0];
	@list2 = split(/_/, $ID);
	$prefix = $list2[0];
	if($max == 0) {
		$max += 1;
		push(@A,$prefix);
	} else {
		for ($i=0;$i<$max;$i++) {
			if($A[$i] eq $prefix) {
				last;
			}
		}
		if($i == $max) {
			$max += 1;
			push(@A,$prefix);
		}
	}
}
close INFILE;
$itemsA = $max;
@As = sort(@A);
for($i=0;$i<$itemsA;$i++){
	$As[$i] .= "\n";
}

print OUT $itemsA . "\n";
print OUT @As;
print OUT "//END";

#end