Need help for a quest

Hi,

I'm presently building a quest, and here's the part where I'm having trouble (beginning of the quest only) :

You click on the button --> 3 enemies spawn.
You kill the 3 enemies ---> 2 enemies spawn.

For each enemy you kill, you get credits. But, here's my problem : I don't know how to make the 2 enemies spawn only after the THREE enemies are dead. I know how to make a npc spawns after another npc is dead : NPC_target. But how can I make this npc (or these npcs, in my case) to spawn ONLY after the THREE enemies are dead, and not just one. So : Once you've killed the enemies, 2 other enemies spawn.

I hope you can help me, thanks a lot!

Nervermind, I know how now.

I have to use a target_counter, and set it to "count,3"