Minimum of two geometric variables

Let $X_1$ and $X_2$ be two independent and identically distributed discrete random variables having the probability mass function $$f(x)=\begin{cases} \left(\frac{1}{2}\right)^x, & x=1, 2, 3, \dots \ 0, & \text{otherwise.} \end{cases}$$ Then $P(\min\{X_1, X_2\} \ge 5)$ equals