#include <iostream>
using namespace std;
struct node{
   node *l,*r; int k;
};

void alter_wrong(node *x){x=NULL;}
void alter_correct(node **x){*x=NULL;}
int main(){
    node *root=new node;
    alter_wrong(root);
    cout<<(root==NULL)<<endl;
    alter_correct(&root);
    cout<<(root==NULL)<<endl;
    return 0;
}