function benchmark_znz_det()
  print("benchmark_znz_det ... ")
  n = 2003 * 1009
  Zn, = residue_ring(ZZ, n)
  R, x = polynomial_ring(Zn, "x")

  M = matrix_space(R, 80, 80)()

  for i in 1:80
    for j in 1:80
      for k in 0:5
        M[i, j] = M[i, j] + x^k * Zn(rand(-100:100))
      end
    end
  end

  tt = @elapsed det(M)
  println("$tt")
end

