modern-cpp-tutorial/exercises/2/fold.expresion.cpp

#include <iostream>
template<typename ... T>
auto average(T ... t) {
    return (t + ... ) / sizeof...(t);
}
int main() {
    std::cout << average(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) << std::endl;
}