Let a function \(f:R\to R\) be defined as \(f(x)=\left{\begin{matrix}\sin x-{e}^{x}\text{ if }x\leq 0 \\ a+[-x]\text{ if…

Let a function \(f:R\to R\) be defined as

\(f(x)=\left{\begin{matrix}\sin x-{e}^{x}\text{ if }x\leq 0 \\ a+[-x]\text{ if }0

where \([x]\) is the greatest integer less than or equal to x. If f is continuous on R, then ( a + b ) is equal to:

[JEE Main 2021, 20 Jul (Shift 1)]