Help me in solving AOJ14 problem : Practice Problem - First and Last

help
,
1

My issue

my method produced right output but when i hit submit it shows me that it’s a wrong answer

My code

import java.util.*;
class Codechef
{
	public static void main (String[] args)
	{
		Scanner read = new Scanner(System.in);
		int t = read.nextInt();
		for(int i=0; i<t; i++)
		{
		    ArrayList<Integer> a = new ArrayList<Integer>();
		    int n = read.nextInt();
		    for(int j=0; j<n; j++){
		        int ele = read.nextInt();
    		    a.add(ele);
		    }
		    // Update your code below this line to solve the problem
		    ArrayList<Integer> b = new ArrayList<Integer>();
		    for(int l=0; l<n; l++){
		        if(l==(n-1)){
		            b.add(0, a.get(l));
		        }
		        else{
		            b.add(l, a.get(l));
		        }
		    }
		    System.out.println(b.get(0)+b.get(b.size()-1));
		    
		}
	}
}

Learning course: Placement preparation using Java
Problem Link: Practice Problem in - CodeChef