6
It wasn't just Lech, Czech & Rus - but Lech, Czech, Rus, Serb & Croat. They threw dice to see who goes where: Poles to the North, Russians to the East, Czechs to the West, Serbs and Croats to the South (as you can see they were unhappy about that at first, but now they like having so many tourists).
Edit:
Translation added (thanks Albobalboa for posting it):
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