for (Integer prime : primes){
            System.out.println(prime);
        }
        int temp = primes.get(0);
        primes.set(0 , primes.get(primes.size()-1));
        primes.set(primes.size()-1,temp);
        System.out.println("/nThe final list ...");
        for (Integer prime : primes){
            System.out.println(prime);
        }
    }
}