Find sum and product of divisible key in linked list

// C Program 
// Find sum and product of divisible key in linked list
#include <stdio.h>

#include <stdlib.h> //for malloc function

//Linked List Node
struct Node
{
	int data;
	struct Node *next;
};
//Create a node of linked list
struct Node *create_node(int data)
{
	//Create dynamic node
	struct Node *node = (struct Node *) malloc(sizeof(struct Node));
	if (node == NULL)
	{
		printf("Memory overflow\n");
	}
	else
	{
		//Set initial node value
		node->data = data;
		node->next = NULL;
	}
	return node;
}
//Add new node at end of linked list 
void add_node(struct Node **head, int data)
{
	struct Node *node = create_node(data);
	if ( *head == NULL)
	{
		*head = node;
	}
	else
	{
		struct Node *temp = *head;
		//Find last node
		while (temp->next != NULL)
		{
			temp = temp->next;
		}
		//Add node at last position
		temp->next = node;
	}
}
//Display linked list element
void display(struct Node *head)
{
	if (head == NULL)
	{
		printf("\n Empty linked list\n");
		return;
	}
	struct Node *temp = head;
	//iterating linked list elements
	while (temp != NULL)
	{
		if (temp != head)
		{
			printf(" →");
		}
		printf(" %d", temp->data);
		//visit to next node
		temp = temp->next;
	}
	printf(" → NULL\n");
}
//Calculate sum and product of nodes which is divisible by given key
void find_sum_product(struct Node *head, int key)
{
	if (head == NULL)
	{
		printf("\n Empty linked List");
	}
	else
	{
		//Display linked list nodes
		printf("\n Linked Linked \n");
		display(head);
		// Define usful resultant variable
		int sum = 0;
		int product = 1;
		int find = 0;
		// Get first node of linked list
		struct Node *auxiliary = head;
		// iterating linked list elements
		while (auxiliary != NULL)
		{
			if (auxiliary->data % key == 0)
			{
				// When node value is divisible by key
				// Active the result status
				find = 1;
				//Calculate the sum of node value
				sum += auxiliary->data;
				//Calculate product
				product *= auxiliary->data;
			}
			// Visit to next node
			auxiliary = auxiliary->next;
		}
		//Display result
		if (find == 1)
		{
			printf(" Given key : %d", key);
			printf("\n Sum       :  %d", sum);
			printf("\n Product   :  %d\n", product);
		}
		else
		{
			printf(" Given key [%d] not exist\n", key);
		}
	}
}
int main()
{
	struct Node *head = NULL;
	// Add linked list node
	//  2 → 9 → 1 → 5 → 6 → 4 → 3 → 7 → NULL
	add_node( &head, 2);
	add_node( &head, 9);
	add_node( &head, 1);
	add_node( &head, 5);
	add_node( &head, 6);
	add_node( &head, 4);
	add_node( &head, 3);
	add_node( &head, 7);
	find_sum_product(head, 3);
	return 0;
}

Output

 Linked Linked
 2 → 9 → 1 → 5 → 6 → 4 → 3 → 7 → NULL
 Given key : 3
 Sum       :  18
 Product   :  162