# speed_pldi10_fig2_2
# C4B:    |[x,n]| + |[z,n]| ticks
# ecoimp: [1 + x + -z | 1 + x + -z ≥ 0] + 2·[n + -x | n + -x ≥ 0]

def startFig2_2():
  var x, z, n

  while x < n:
    tick 1
    if z > x:
      x = x + 1
    else:
      z = z + 1