Let f, g : R R be functions defined by
f(x) = \left\{ {\matrix{
{[x]} & , & {x < 0} \cr
{|1 - x|} & , & {x \ge 0} \cr
} } \right. and g(x) = \left\{ {\matrix{
{{e^x} - x} & , & {x < 0} \cr
{{{(x - 1)}^2} - 1} & , & {x \ge 0} \cr
} } \right. where [x] denote the greatest integer less than or equal to x. Then, the function fog is discontinuous at exactly :