Markov Chains & Long-Run Behavior · Easy problem

A chain on states 1, 2, 3, 4 has transition matrix $M = \begin{pmatrix} 1 & 1/4 & 0 & 0 \\ 0 & 1/2 & 0 & 1/3 \\ 0 & 0 & 1 & 1/3 \\ 0 & 1/4 & 0 & 1/3 \end{pmatrix}$, where $M_{ij}$ is the probability of moving to state $i$ from state $j$. How many of the four states are absorbing?