What is the output of the following C++ program?#include using namespace std; struct A { A() { cout

What is the output of the following C++ program?

#include <iostream>
using namespace std;
struct A { A() { cout << 1; } ~A() { cout << 3; } };
struct B : A { B() { cout << 2; } ~B() { cout << 4; } };
int main() { B x; }