include iostream using namespace std template size_t auto average auto

#include <iostream>

using namespace std;

template <size_t S> auto average(auto (&array)[S], int n = S) {
    if (n == 1) {
        return array[0];
    } else {
        return ((n - 1) * average(array, n - 1) + array[n - 1]) / n;
    }
}

int main() {
    double array[6] = {1, 2, 3, 5, 7, 8};
    cout << average(array);
}