(STA CASA - 1983) Seja a função $\;f\;$, de $\,{\rm I\!R}\,$ em $\,{\rm I\!R}\,$, definida por:
$\,f(x)\;=\;\left\{\begin{array}{rcr} -2x\,+\,1\phantom{XX}{\text se\;\;}\;x\,\leqslant\,0\;& \\ x\,+\,1\phantom{XX}{\text se\;\;}\;x\,\gt\;0\;& \\ \end{array} \right.\,$
A soma $\phantom{X}f\left(- \dfrac{\,1\,}{\,2\,}\right)\,+\,f(0)\,+\,f(1)\phantom{X}$ é igual a: