write a function string differentiation $($string exp$)$ in c$++$ to compute differentiation single variable polynomial expression "exp" given as input given as divide and conquer approach this function should return the differentiation of input string $.$ assume that a function string $,$ 'differentiate $($string $5)\text{'}$ already exsit which computes and returns the differentiation of single term without any coefficient

for example: differentiate$($x$^2)$ returns $2$x$.$

differentiate$($ e$^-$x$)$ returns $-$e$^-$x