#!/usr/bin/perl
use strict;
use warnings;

my (@genes, %tested);
while (<>) {
    s/^>//;
    
    my ($col1, $col2) = split;
    push @genes, $col1;
    $tested{$col2}++; 
}

{
    local $\ = "\n";
    for (@genes) {
        print if not $tested{$_};  
    }
}