  Integral simplicial volume is a homotopy invariant of oriented closed
connected manifolds, defined as the minimal weighted number of singular
simplices needed to represent the fundamental class with integral coefficients.
We show that odd-dimensional spheres are the only manifolds with integral
simplicial volume equal to 1. Consequently, we obtain an elementary proof that,
in general, the integral simplicial volume of (triangulated) manifolds is not
computable.
