2
3
1 2 3
4
1 5 7 2

0
-5

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[3017];
        int t, n;
         t = cin.nextInt();

         while(t--){
            n = cin.nextInt();

            for (int i = 0; i < n; i++)
                a[i] = cin.nextBigInteger();
            
            BigInteger ans = BigInteger.ZERO;
            BigInteger c =  BigInteger.ONE; 

            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);
        }
    } 
}