- Solution

#include <array>
#include <iostream>
int main(){
  std::cout << std::endl;
  std::array<int, 4> arr = {1, 2, 3, 4};
  for (auto a: arr){ std::cout << a << " " ; }
  arr[1]=1000;
  arr[5]=5;
  std::cout << std::endl;
  for (auto a: arr){ std::cout << a << " " ; }
  arr.at(0) = 10000;
  arr.at(5) = 5;
  std::cout << std::endl;
}