How to port Unity shader to Unreal Engine material?

I’m new to UE4 and not good at shader programming.
But, I really want to port Unity shader to UE 4.

There’s some shader code for Unity here :

inline float Linear01Depth( float z )
return 1.0 / (_ZBufferParams.x * z + _ZBufferParams.y);

float2 pixelSize = 1.0 / _ScreenParams.xy;
float depth = Linear01Depth( tex2D( _CameraDepthTexture, i.uv).r);

The problem is I don’t know how I can replace to UE4.
So please, someone let me know how I replace these elements like _ZBufferParams, _ScreenParams, _CameraDepthTexture in Unity to UE4 material?