def main():
  field x = 2**4
  assert(x == 16)
  x = x**2
  assert(x == 256)
  field y = 3**3
  assert(y == 27)
  field z = y**2
  assert(z == 729)
  field a = 5**2
  assert(a == 25)
  a = a**2
  assert(a == 625)
  a = 5**5
  assert(a == 3125)
  return