3. There are $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}, \mathbf{E}$ five people, each of whom always tells lies or always tells the truth, and they all know each other's behavior. $\mathrm{A}$ says $\mathrm{B}$ is a liar, $\mathrm{B}$ says $\mathrm{C}$ is a liar, $\mathrm{C}$ says $\mathrm{D}$ is a liar, $\mathrm{D}$ says $\mathbf{E}$ is a liar. Then, among these five people, what is the maximum number of liars?
【Analysis】If A tells the truth, from what A says, we know B is lying, from what B says, we know C is telling the truth, and so on, we find D is lying and E is telling the truth, which means 2 people are lying.
If A is lying, then B is telling the truth, C is lying, D is telling the truth, and E is lying, which means 3 people are lying. Therefore, there are at most 3 liars.