Answer:
You should greet one by one.
Step-by-step explanation:
Uruguay is a country with a different culture than other countries so you have to be careful when trying to greet people at a small party or at a small event. Otherwise you will be labeled as a bad mannered person. So the best thing you could do in Uruguay is to say "hi" to every person who is there.
For example:
There are five people there, you can't greet everyone as a group so you have to say "hello" to every member of the group.