1 3 5 1 2 3 1 1 2 2 1 2 3 1 5 1 3 4 1 2
3 Hint: At the beginning, community $1$ has 1 guy, $2$ has 2 guys, $3$ has 3 guys. Operation 1: build a bridge between $1$ and $2$ Operation 2: remove the bridge between $1$ and $2$. Operation 3: back to state $1$, which has bridge between $1$ and $2$. Operation 4: change the number of community $1$ from $1$ to $5$. Operation 5: enquire the combinations of community $1$ and $2$. Obviously, the answer is 3.