The hedge ratio of an at$-$the$-$money call option on IBM is $0\mathrm{.}35.$ The hedge ratio of an at$-$the$-$money put option is $-0\mathrm{.}65.$ What is the

hedge ratio of an at$-$the$-$money straddle position on IBM?

Note: Negative answer should be indicated by a minus sign. Round your answer to $2$ decimal places.

Hedge ratio