What happens when both of the following C++ programs are compiled and executed?

===== Program 1 =====
#include <iostream>
#include <array>
 
using namespace std;
 
int main()
{
	array<int,5> arr1;
	arr1.fill(5);
	cout<<get<5>(arr1);
	return 0;
}
=====================
===== Program 2 =====
#include <iostream>
#include <array>
 
using namespace std;
 
int main()
{
	array<int,5> arr1;
	arr1.fill(5);
	cout<<arr1.at(5);
	return 0;
}
=====================