Bipartite Graphs and Matchings · Easy problem

In a small village of eight people, residents $1,2,3,4,5$ can each be paired with a well as follows: $1$ and $2$ can only use well $a$; $3$ and $4$ can only use well $b$; $5$ can only use well $c$ (wells $a,b,c$ count as $3$ more people in this network for a total of $8$). What is the size of a maximum independent set — the largest group of these $8$ "people" with no pairing possible between any two of them?