a1(10, 20) < a1(10, 21)
a1(10, 20) = a1(10, 20)
a1(10, 20) > a1(9, 20)
a2(10, 20) > a2(10, 19)
a2(10, 20) = a2(10, 20)
a2(10, 20) < a2(11, 20)
a2(10, 20) < b2(10)
b2(30) > a2(50, 40)
b2(30) > b2(29)
b2(30) = b2(30)
b2(30) < b2(31)
a3(10, 20) > a3(10, 19)
a3(10, 20) = a3(10, 20)
a3(10, 20) < a3(11, 20)
a3(10, 20) < b3(10)
a3(10, 20) < c3
b3(30) > a3(50, 40)
b3(30) > b3(29)
b3(30) = b3(30)
b3(30) < b3(31)
b3(30) < c3
c3 > a3(50, 40)
c3 > b3(50)
c3 = c3