Rotate camera to character angle

Hi! I'm making 3rd person adventure. I have a full (360) rotation camera with little And i'm trying to make csript wich:

a) Player pressing any movement buttons (AWSD)

b) Script Get information about Z-vector (forward direction) from character prefab (target) in scene.

c) Then script Give it to MainCamera

d) Finaly rotate Main Camera to the same angle as character.

In the and when we pressing any movement buttons camera reset it angle behind character. I just don't know how to make it, i've try a lot of variantations but still nothing. Can someone help me? Thanks.