The integral is 1.83333 with estimated absolute error 2.03541e-14
The contributions of the subregions are:
  Walls: integral = 0.666667, error = 7.40149e-15
  Roof:  integral = 1.16667 , error = 1.29526e-14
The exact value is 2/3 + 7/6 = 11/6
74 function evaluations were used.
