# How many RAW dependencies are present in these instructions?

What is the number of RAW dependencies in below set of instructions?

I1: R1 = R2 - R3 I2: R2 = R1 + R3 I3: R3 = R1 + R2 I4: R1 = R2 - R2

I can see the following RAW dependencies in it:

$$I_2-I_1\ for\ R_1$$ ……… (a)

$$I_3-I_1\ for\ R_1$$ ……… (b)

$$I_3-I_2\ for\ R_2$$ ……… (c)

$$I_4-I_2\ for\ R_2$$ ……… (d)

I think taking (a) and (b) implies that (c) has already been included. So, should this be counted as 4 RAW dependencies or 3 RAW dependencies?