Diffeomorphic to $\mathbb{R}^2\times S^1$

Question

Let $M_c=\{(x_1, x_2, x_3, x_4)\in \mathbb{R}^4 \ |\ x_1x_2+x_2x_3+x_3x_4=c\}.$

Prove that $M_c$ is diffeomorphic to $\mathbb{R}^2\times S^1$ if $c\neq 0$ .

I tried to get a diffeomorphic mapping, but I couldn't think of anything.

Please tell me how to get the map.