#include <stdio.h>
#include <stdlib.h>
 
typedef struct node {
    int val;
    struct node *next;
} Node;
 
Node *head = NULL;
 
void insHead(int x) {
    Node *p;
    p = (Node *)malloc(sizeof(Node));
    p->next = head;  // A
    p->val = x;      // B
    head = p;
}
 
void printL() {
    Node *p = head;
    while (p != NULL) {
        printf("%d ", p->val);
        p = p->next;
    }
}
 
int main(void) {
    insHead(1);
    insHead(2);
    insHead(2);
    insHead(3);
    printL();
    return 0;
}

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