open(FILE2,">file1.txt")|| warn "Could not open\n";

open(FILE3,"file2.txt")|| warn "Could not open\n";

my $Previous = "";
my @data = <FILE3>;

	$index=0;
	foreach $_data (@data) 
	{
		$index++;
		chomp ($_data);
                @Current = split(/\t/, $_data);
		@Previous = split(/\t/, $Previous);
		if (@Current[0] ne @Previous[0])
		{
			if ($index == 1)
			{	
				# do nothing.	
			}
			else
			{
				print FILE2 $Previous;
			}

		}

                else {} 

		$Previous = $_data;
	             
        }

close(FILE2);
close(FILE3);