make_x_monotone 5 1 1 10
# make_x_monotone 0 1 1 0
# make_x_monotone 1 2 1 1 1 2
# make_x_monotone 2 3 1 0 1 3 1 4
# make_x_monotone 3 2 1 5 1 6
# make_x_monotone 4 3 1 7 1 8 1 9
# make_x_monotone 6 9 1 11 1 12 1 13 1 14 1 15 1 16 1 17 1 18 1 19
