CAT 2024 Surds and Indices — Previous Year Question

The sum of all real values of $k$ for which $\left(\frac{1}{8}\right)^k \times\left(\frac{1}{32768}\right)^{\frac{1}{3}}=\frac{1}{8} \times\left(\frac{1}{32768}\right)^{\frac{1}{k}}$ , is