An invisible U+00ad character is hidden there as the variable name.

• (int) was added to cast vector.size() to type int from unsigned long or std::size_t. If you don't add it, there will be compile time warning.
• std::pow is the standard C++ function. pow was derived from C stdlib.

To avoid copying of a std::vector

[updated wiki link](https://en.wikipedia.org/wiki/Guard_(computer_science)

Re-raised as an issue.