#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

typedef struct{
    char name[100];
} element;

typedef struct ListNode{
    element data;
    struct ListNode *link;
} ListNode;

element delete_first(ListNode *head){
    ListNode *removed;
    element data;

    if (head == (ListNode *)NULL)
        return;
    removed=head->link;
    data=removed->data;
    if(head==removed)
        head=NULL;
    else
        head->link=removed->link;
    free(removed);
    return data;
}

ListNode* insert_last(ListNode* head, element data){
    ListNode *node = (ListNode *)malloc(sizeof(ListNode));
    node->data = data;
    if (head == NULL) {
        head =  node ;
        node->link = head;
    }
    else {
        node->link = head->link;    
        head->link = node;      
        head =  node;      
    }
    return head;
}

void print_list(ListNode* head){
    ListNode* p;

    if (head == NULL)
        return;
    p = head->link;
    do {
        printf("%s->", p->data);
        p = p->link;
    } while (p!= head);
    printf("%s->", p->data);
    printf("\n");
}

int main(void){
    ListNode *head = NULL;
    element data;

    strcpy(data.name, "KIM");
    head=insert_last(head, data);
    print_list(head);

    strcpy(data.name, "PARK");
    head=insert_last(head, data);
    print_list(head);

    strcpy(data.name, "CHOI");
    head=insert_last(head, data);
    print_list(head);

    data=delete_first(head);
    printf("%s\n", data.name);
    data=delete_first(head);
    printf("%s\n", data.name);
    data=delete_first(head);
    printf("%s\n", data.name);

    return 0;
}