给定如下C++代码：

#include <iostream>
using namespace std;

int g_num = 100;

void test() {
    int g_num = 200;
    {
        int g_num = 300;
        cout << g_num << endl;
    }
    cout << g_num << endl;
}

int main() {
    test();
    cout << g_num << endl;
    return 0;
}