  We use Algorithmic Differentiation (AD) to implement type-generic tangent and
adjoint versions of $$ y=\sum_{i=0}^{n-1} x_{2 i} \cdot x_{2 i+1} $$ in C++. We
run an instantiation for char-arithmetic and we print the gradient at
$(101~77~114~114~32~121~109~88~115~97)^T$ to std::cout, yielding the output
``Merry Xmas''.
  Similar instantiations of type-generic second-order tangent and second-order
adjoint versions of $$
  y=\frac{1}{6} \cdot \sum_{i=0}^{n-1} x^3_{i} $$ yield ``Happy 2024'' at
$(72~97~112~112~121~32~50~48~50~52)^T.$ Prepend a sufficiently large number of
zeros to the input vector to explore the varying run times of the different
derivative codes. The entire source code can be found on
https://github.com/un110076/SeasonsGreetings.
