how can i reproduce the 'Unity_Matrix_VP' value?

I wan't to calculate the Unity_Matrix_VP in C# code.

But, always I got the incorrect result. My code as follow:

             Matrix4x4 V = camera1.worldToCameraMatrix;
         Matrix4x4 P = camera1.projectionMatrix;
         var N = new Matrix4x4();
         N.SetRow(0, new Vector4(1.0f, 0.0f, 0.0f, 0.0f));
         N.SetRow(1, new Vector4(0.0f, 1.0f, 0.0f, 0.0f));
         N.SetRow(2, new Vector4(0.0f, 0.0f, -1.0f, 0.0f));
         N.SetRow(3, new Vector4(0f, 0f, 0f, 0f));
         Debug.Log("testCamera");
         Debug.Log(N);
         Debug.Log(P * N * V);
 

My Code result is:

 0.97384    -0.02902    0.00304    3.04939
 0.05073    1.72168    0.18231    179.67620
 0.00624    0.10518    -0.99504    -990.16710
 0.00623    0.10512    -0.99444    -989.57320

But, the value of Unity_Matrix_VP from FrameDebugger is another value:

It amazing me. So Unity calculate it's unity_Matrix_VP value via another method?