typedef struct node {
    int data;
    struct node *next;
} nodal;

nodal *distance(nodal *start) {
    int n1, n2, d1 = 0, d2 = 0, length = 0;
    if (start == NULL) {
        printf("List is empty\n");
    } else {
        printf("\nEnter the fist node element : ");
        if (scanf("%d", &n1) != 1) {
            printf("invalid input\n");
            return start;
        }
        printf("\nEnter the second node element : ");
        if (scanf("%d", &n2) != 1) {
            printf("invalid input\n");
            return start;
        }
        nodal *ptr = start;
        for (;;) {
            length++;
            if (ptr->data == n1 && !d1) {
                d1 = length;
            } else if (ptr->data == n2) {
                if (d1) {
                    d2 = length;
                    break;
                }
                if (!d2)
                    d2 = length;
            }
            ptr = ptr->next;
            if (ptr == start)
                break;
        }
    }
    if (d1 && d2) {
        int dist = d2 - d1;
        if (dist < 0)
            dist += length;
        printf("The distance between node(%d) and node(%d) is %d\n", d1, d2, dist);
    } else {
        if (d2)
            printf("node(%d) not found\n", d1);
        if (d1)
            printf("node(%d) not found\n", d2);
    }
    return start;
}