  We consider the massive Thirring model at finite density in 0+1 dimension.
The fermion bag approach, Langevin dynamics and complex Langevin dynamics are
adopted to attack the sign problem for this model. Compared with the complex
Langevin dynamics, both fermion bag approach and Langvin dynamics avoid the
sign problem. The fermion density and chiral condensate, which are obtained by
these numerical methods, are compared with the exact results. The advantages of
the fermion bag approach over the other numerical methods are also discussed.
