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

typedef struct Node{
    int n;
    struct Node* next
} N;

int rem(N** head, int key);
void pl(N* node);

int main()
{
    N* head = (N*)calloc(1, sizeof(N));
    head->next = (N*)calloc(1, sizeof(N));
    head->next->next = (N*)calloc(1, sizeof(N));
    head->next->next->next = (N*)calloc(1, sizeof(N));
    head->next->next->next->next = (N*)calloc(1, sizeof(N));
    //
    head->n = 1;
    head->next->n = 2;
    head->next->next->n = 3;
    head->next->next->next->n = 4;
    head->next->next->next->next->n = 5;
    pl(head);
    //delete first item
    rem(&head, 1);
    pl(head);
    //delete last
    rem(&head, 5);
    pl(head);

    //del Mid
    rem(&head, 3);
    pl(head);

    //del mid
    rem(&head, 3);
    pl(head);

    //del
    rem(&head, 2);
    pl(head);

    //del last
    rem(&head, 4);
    pl(head);

    printf("%d\n", head);

    return 0;
}


int rem(N** head, int key)
{
    N** outside = head;
    N* temp;

    while((temp = *outside)){
        if(temp->n == key){
            *outside = temp->next;
            free(temp);
            return 1;
        } else {
            outside = &temp->next;
        }
    }
    return -1;
}

void pl(N* node){
    while(node){
        printf("[%d] ", node->n);
        node = node->next;
    }
    printf("\n");
}