# Checker for S4(17)
chor 1 2
chor 2 3
mu 1 2 3
chor 3 145
mu 3 2 4
mu 3 4 5
chor 5 5

# [a, bab] has order > 17, so a must be 2B
mu 2 3 6
com 1 6 7
chor 7 18