If z_1, z_2 are complex numbers such that Re (z_1)=|z_1-1|, Re (z_2)=|z_2-1| and (z_1-z_2)=(π)/6, then Im (z_1+z_2) is equal to:

If $\displaystyle z_1, z_2$ are complex numbers such that $\displaystyle \operatorname{Re}\left(z_1\right)=\left|z_1-1\right|, \quad \operatorname{Re}\left(z_2\right)=\left|z_2-1\right|$ and $\displaystyle \arg \left(z_1-z_2\right)=\frac{\pi}{6}$, then $\displaystyle \operatorname{Im}\left(z_1+z_2\right)$ is equal to :