Insert a node at last nth position of linked list in c

C program for insert node in nth last position in linked list. Here Problem description and explanation.

/*
    C program for
    Linked list insert node at last nth position
*/
#include <stdio.h>
#include <stdlib.h>

// Linked List LinkNode
struct LinkNode
{
    int data;
    struct LinkNode * next;
};
// Singly linked list 
struct SingleLL
{
    struct LinkNode * head;
};
// Returns the new linked list
struct SingleLL * newLinkedList()
{
    // Create memory of head and tail Nodes
    struct SingleLL * sll = (struct SingleLL * )
    malloc(sizeof(struct SingleLL));
    if (sll == NULL)
    {
        printf("Memory overflow\n");
    }
    else
    {
        sll->head = NULL;
    }
    return sll;
}
// Returns a new linked list node
struct LinkNode * newLinkedNode(int data)
{
    struct LinkNode * node = (struct LinkNode * )
    malloc(sizeof(struct LinkNode));
    if (node == NULL)
    {
        printf("Memory overflow to create node\n");
    }
    else
    {
        // Set node values
        node->data = data;
        node->next = NULL;
    }
    return node;
}
// Display linked list element
void display(struct LinkNode * node)
{
    if (node == NULL)
    {
        return;
    }
    struct LinkNode * temp = node;
    // iterating linked list elements
    while (temp != NULL)
    {
        printf(" %d →", temp->data);
        // Visit to next node
        temp = temp->next;
    }
    printf(" NULL\n");
}
// Handles the request of adding new node at end of linked list
void addNode(struct SingleLL * sll, int data)
{
    // Create dynamic node
    struct LinkNode * node = newLinkedNode(data);
    if (node == NULL)
    {
        // Handle memory overflow 
        printf("Memory overflow to Create LinkNode\n");
        return;
    }
    if (sll->head == NULL)
    {
        // First node in linked list
        sll->head = node;
    }
    else
    {
        struct LinkNode * temp = sll->head;
        // Find the last node
        while (temp != NULL && temp->next != NULL)
        {
            temp = temp->next;
        }
        // Add node at last position
        temp->next = node;
    }
}
// Add node at the last nth possition
void add_nth_last(struct SingleLL * sll, int nth, int value)
{
    if (sll->head == NULL)
    {
        printf("\nEmpty Linked List");
    }
    else if (nth <= 0)
    {
        printf("\nPlease give of a valid node position");
    }
    else
    {
        struct LinkNode * temp = sll->head;
        struct LinkNode * location = NULL;
        while (temp != NULL)
        {
            nth--;
            if (nth <= 0)
            {
                if (location == NULL)
                {
                    location = sll->head;
                }
                else
                {
                    location = location->next;
                }
            }
            temp = temp->next;
        }
        if (nth > 1)
        {
            // When not possible to add node
            printf("\nInvalid position");
        }
        else
        {
            // Create new node
            struct LinkNode * node = newLinkedNode(value);
            if (node != NULL)
            {
                if (location == NULL)
                {
                    // insert node at begining
                    node->next = sll->head;
                    sll->head = node;
                }
                else
                {
                    node->next = location->next;
                    location->next = node;
                }
                // Display all node
                display(sll->head);
            }
        }
    }
}
int main(int argc, char
    const * argv[])
{
    struct SingleLL * sll = newLinkedList();
    // Linked list
    // 5 → 4 → 3 → 2 → 1 → NULL
    addNode(sll, 5);
    addNode(sll, 4);
    addNode(sll, 3);
    addNode(sll, 2);
    addNode(sll, 1);
    printf("Before Linked List node : \n");
    display(sll->head);
    // Assume that position is positive integer
    int nth = 2, data = 10;
    printf("After insert node at %d last position : \n", nth);
    add_nth_last(sll, nth, data);
    return 0;
}

Before Linked List node :
 5 → 4 → 3 → 2 → 1 → NULL
After insert node at 2 last position :
 5 → 4 → 3 → 2 → 10 → 1 → NULL