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