#include<stdio.h>
#include<stdlib.h>
struct node {
    int data;
    struct node*Next;
    {
    *head=NULL,*tail;
int main()
{
    int k;
    scanf("%d",&k);
    if(n-k=0)
    print("list is emoty");
    else if (n-k<0)
    printh("Invalid input");
    else
    {
    
}