The number of complex numbers \( z \), satisfying \( |z| = 1 \) and \(\displaystyle \left| \frac{z}{\overline{z}} + \frac{\overline{z}}{z} \right| = 1 \), is:
\( 6 \)
\( 4 \)
\( 10 \)
\( 8 \)