#include <iostream>
using namespace std;

void print_boxes(int n)
{
    if (n <= 0) {
        return;
    }
    cout << "[]";
    print_boxes(n - 1);
}

int main()
{
    print_boxes(4);
    cout << "\n" << " Expected: [][][][]" << endl;
    print_boxes(4);
    return 0;
}