Nginx, how to block countries but not crawlers?

Question

Nginx

Good day!
Please tell me the correct nginx config for blocking countries and at the same time for skipping search robots (by user-agent). Needed to fight DDoS.
Blocking by country, as far as I understand, will be like this:

geoip_country /usr/share/GeoIP/GeoIP.dat;
map $geoip_country_code $bad_country {
    default 1;
    include geo/good_countries;
}

location / {
       if ($bad_country){
              return 403;
       }
}

And where can I put the second condition about the user-agent pass of search robots?