Let $\mathrm { f } ( \mathrm { x } ) = 2 ^ { \mathrm { x } } - \mathrm { x } ^ { 2 } , \mathrm { x } \in \mathrm { R }$. If m and n are respectively the number of points at which the curves $\mathrm { y } = \mathrm { f } ( \mathrm { x } )$ and $\mathrm { y } = \mathrm { f } ^ { \prime } ( \mathrm { x } )$ intersects the x-axis, then the value of $\mathrm { m } + \mathrm { n }$ is