Given the generator matrix $$ G(z) = \begin{bmatrix} 1 & 1 & 1 \\ z-1 & z-2 & 2z-3 \end{bmatrix}$$
I know the rate is 2/3 and that the convolutional code is of degree 1 over $F_5$. What is not so clear to me is how to find the free distance.
I already considered the problem here: Free distance of a convolutional code but unfortunately, I don't understand how they got the free distance 5 in their exercice...
So I'd appreciate any comprehensible answer!