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

struct Node{
    int x;
    struct Node *next;
};

void display(struct Node *head){
    while(head!=NULL){
        printf("%d \n", head->x);
        head=head->next;
    }
}

int main(){
    struct Node *head;
    head = malloc(sizeof(struct Node));

    struct Node *tail;
    tail=head;

    for(int i=-20;i<21;i=i+5){
        struct Node *tmp;
        tmp=malloc(sizeof(struct Node));
        tmp->x = i;

        tail->next=tmp;
        tmp->next=NULL;
        tail=tmp;
    }
    display(head);

    while(head!=NULL){
        struct Node *tmp = head;
        tmp=head->next;
        free(head);
        head=tmp;
    }
}