sort stack with c

#include <stdio.h> 
#include <stdlib.h> 
  
struct stack { 
    int data; 
    struct stack* next; 
}; 
  
void initStack(struct stack** s) { *s = NULL; } 
  

int isEmpty(struct stack* s) 
{ 
    if (s == NULL) 
        return 1; 
    return 0; 
} 
  
void push(struct stack** s, int x) 
{ 
    struct stack* p = (struct stack*)malloc(sizeof(*p)); 
  
    if (p == NULL) { 
        fprintf(stderr, "Memory allocation failed.\n"); 
        return; 
    } 
  
    p->data = x; 
    p->next = *s; 
    *s = p; 
} 
  
int pop(struct stack** s) 
{ 
    int x; 
    struct stack* temp; 
  
    x = (*s)->data; 
    temp = *s; 
    (*s) = (*s)->next; 
    free(temp); 
  
    return x; 
} 
  

int top(struct stack* s) { return (s->data); } 
   
void sortedInsert(struct stack** s, int x) 
{ 
   
    if (isEmpty(*s) || x > top(*s)) { 
        push(s, x); 
        return; 
    } 
  
  
    int temp = pop(s); 
    sortedInsert(s, x); 
  
   
    push(s, temp); 
} 
  

void sortStack(struct stack** s) 
{ 
      if (!isEmpty(*s)) { 
                int x = pop(s); 
  
         sortStack(s); 
  
               sortedInsert(s, x); 
    } 
} 
  

void printStack(struct stack* s) 
{ 
    while (s) { 
        printf("%d ", s->data); 
        s = s->next; 
    } 
    printf("\n"); 
} 
  
int main(void) 
{ 
    struct stack* top; 
  
    initStack(&top); 
    push(&top, 30); 
    push(&top, -5); 
    push(&top, 18); 
    push(&top, 14); 
    push(&top, -3); 
  
    printf("Stack elements before sorting:\n"); 
    printStack(top); 
  
    sortStack(&top); 
    printf("\n\n"); 
  
    printf("Stack elements after sorting:\n"); 
    printStack(top); 
  
    return 0; 
}