Let $(X,\omega)$ be a surface and $\pi:X\rightarrow B_{0}={\bf R}$ be an arbitrary smooth proper function with isolated critical points. Then $(X,\pi,B_{0})$ is an integrable system. Space $B$ of connected components of fibers is a graph, and ${\bf Z}$-affine structure on $B^{sm}\subset B$ gives a length element on edges of $B$.