import java.util.Scanner;

import java.math.BigInteger;

 

public class Main {

    public static void main(String[] args) { 

        Scanner cin =  new Scanner(System.in); 

 

        BigInteger[] a;

        a = new BigInteger[3005];

 

        int cas, n;

        cas    = cin.nextInt();;

 

        for (int k = 0; k < cas; k++) {

            n = cin.nextInt();

 

            for (int i = 0; i < n; i++)

                a[i] = cin.nextBigInteger();

            BigInteger ans = BigInteger.valueOf(0);

            BigInteger c = BigInteger.valueOf(1);;

 

            for (int i = 0; i < n; i++) {

                BigInteger tmp = c.multiply(a[n-i-1]);

 

                if (i%2 == 0)

                    ans = ans.add(tmp);

                else

                    ans = ans.subtract(tmp);

 

                tmp = c.multiply(BigInteger.valueOf(n-i-1));

                c = tmp.divide(BigInteger.valueOf(i+1));

            }

 

            System.out.println(ans);

        }

    } 

}