  We study pairing correlations in ultrasmall superconductor in the nanoscopic
limit by means of a toy model where electrons are confined in a single,
multiply degenerate energy level. We solve the model exactly to investigate the
temperature and magnetic field dependence of number parity effect (dependence
of ground state energy on evenness or oddness of the number of electrons). We
find a different parity effect parameter to critical temperature ratio (=~ 4
rather than 3.5) which turns out to be consistent with exact solution of the
BCS gap equation for our model. This suggest the equivalence between the parity
effect parameter and the superconducting gap. We also find that magnetic field
is suppressed as temperature increases.
