chor 1 2
chor 2 3
mu 1 2 3
chor 3 43
com 1 2 4
chor 4 4
pwr 3 3 5
mu 2 5 6
com 1 6 7
chor 7 3
mu 3 3 8
iv 2 9
mu 1 9 10 # ab^-1
mu 8 10 11
mu 3 11 12
mu 12 11 13
pwr 3 10 14
mu 5 14 15
pwr 3 15 16
mu 13 16 17
chor 17 1