diff --git a/BS-Snper.pl b/BS-Snper.pl
index f75140d..64a0289 100755
--- a/BS-Snper.pl
+++ b/BS-Snper.pl
@@ -126,6 +126,7 @@ =head1 Exmple
 while(<INTV>){
 	chomp;
 	my @a=split;
+	next unless(/^\@SQ/);
 	my ($chr,$length);
 	if(/SN\:(\S+)/){
 		$chr=$1;