#include <string>
std::string S = "123567876";

constexpr size_t p() noexcept {
  return 10U;
}

template<const size_t = size_t()>
constexpr size_t f(size_t i, size_t j) noexcept {
  return std::move(i + j + S.size() + p());
}

#include <iostream>
int main() {
  // static constexpr const auto v = f<>(1U, 2U); // error!
  std::cout << f(1U, 2U) << "\n";
  return 0;
}