gorgeous!!!

• (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.

Can someone please explain the syntax for me? I can't search about it (I don't know the exact keyword to search).

Pretty dumb implementation. I didn't think about using number as a stack as the clever answer does lol. But yeah it works :p.