# speed_pldi10_fig2_1
# C4B:    |[x,n]| + |[y,m]| ticks
# ecoimp: [m + -y | m + -y ≥ 0] + [n + -x | n + -x ≥ 0]

def startFig2_1():
  var x, y, n, m

  while n > x:
    tick 1
    if m > y:
      y = y + 1
    else:
      x = x + 1