[ white ]

[ gray ]

[ black ]

[ 3 pairs [white + white + black] ]

[ 3 pairs [gray + gray + black] ]

[ 2 pairs [black + black] ]

[ 2 pairs [white + white] ]

[ 2 pairs [grey + white] ]

[ 2 pairs [black + gray] ]

[ 2 pairs [black + white] ]

[ 2 pairs [gray + gray] ]

[ 3 pairs [black + gray + white] ]

[ 3 pairs [black + black + white] ]

[ 3 pairs [gray + gray + white] ]

[ 3 pairs [black + black + gray] ]