  The early acceleration of protons and electrons in the nonrelativistic
collisionless shocks with three obliquities are investigated through 1D
particle-in-cell simulations. In the simulations, the charged particles
possessing a velocity of $0.2\, c$ flow towards a reflecting boundary, and the
shocks with a sonic Mach number of $13.4$ and a Alf\'{v}en Mach number of
$16.5$ in the downstream shock frame are generated. In these quasi-parallel
shocks with the obliquity angles $\theta = 15^\circ$, $30^\circ$, and
$45^\circ$, some of the protons and the electrons can be injected into the
acceleration processes, and their downstream spectra in the momentum space show
a power law tail at a time of $1.89\times10^5 \omega_{\rm pe}^{-1}$, where
$\omega_{\rm pe}$ is the electron plasma frequency. Moreover, the charged
particles reflected at the shock excite magnetic waves upstream of the shock.
The shock drift acceleration is more prominent with a larger obliquity angle
for the shocks, but the accelerated particles diffuse parallel to the shock
propagation direction more easily to participate in the diffusive shock
acceleration. At the time still in the early acceleration stage, more energetic
protons and electrons appear in the downstream of the shock for $\theta =
15^\circ$ compared with the other two obliquities; moreover, in the upstream
region, the spectrum of the accelerated electrons is the hardest for
$\theta_{\rm nB} = 45^\circ$ among the three obliquities, whereas the proton
spectra for $\theta_{\rm nB} = 15^\circ$ and $45^\circ$ are similar as a result
of the competition of the effectiveness of the shock drift acceleration and the
diffusive shock acceleration.
