import java.util.*;
public class Main
{
public static void main(String[] args) {
System.out.println("Enter the set of students");
Scanner s=new Scanner(System.in);
int setn=s.nextInt();
if(setn<=0)
{
System.out.println(setn+" is an invalid size");
return;
}
System.out.println("Enter the roll number");
int[] rolls=new int[setn];
int oddflag=0;
for(int i=0;i<setn;i++)
{
rolls[i]=s.nextInt();
if(rolls[i]<0)
{
System.out.println(rolls[i]+" is an invalid roll number");
return;