#include <array>
#include <utility>
#include <iostream>
 
template <std::size_t N, std::size_t ... Is>
constexpr std::array<char, N - 1>
to_array(const char (&a)[N], std::index_sequence<Is...>)
{
    return {{a[Is]...}};
}
 
template <std::size_t N>
constexpr std::array<char, N - 1> to_array(const char (&a)[N])
{
    return to_array(a, std::make_index_sequence<N - 1>());
}
 
int main() {
	constexpr std::array<char, 5> a = to_array("hello");
 
	for (auto c: a) {
		std::cout << c;
	}
}

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