public Collection<Player> getOwners() {
		Collection<Player> playerList = new ArrayList<Player>();
		for(int i=0; i<GameConstants.WORLDSIZE; i++){
			for(int n=0; n<GameConstants.WORLDSIZE; n++){
				if(getCityAt(new Position(i,n)) != null){
					playerList.add(getCityAt(new Position(i,n)).getOwner());
				}
			}
		}
		return playerList;
	}