mu 1 2 3
mu 3 2 4
mu 3 4 5
mu 3 5 6
mu 6 3 7
mu 7 4 8
mu 2 8 9
mu 5 5 6
mu 5 6 7
iv 7 6
mu 6 9 8
mu 8 7 2
mu 4 4 5
mu 4 5 6
mu 5 6 7
iv 7 8
mu 8 1 9
mu 9 7 1