Mathematical expressions usually use infix notation in which the operator is in between the

operands: $(1+(2*3)).$ With prefix notation, the operator comes first: $(+1(*23)).$

You are to write a program that evaluates expressions written in prefix notation. The values will

be all integers and the only operators you need to handle are $+,-,*,$ and $/,$ all of which retain

their traditional meanings.

Note that with prefix notation, we are not limited to just two operands. That is$,$ we can add any

number of values: $(+1234)$ evaluates to $10.$ This also works for $-$ and $/.(-10123)$ is

interpreted as $10-1-2-3$ and evaluates to $4.$