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