import java.math.BigInteger;
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        int t = in.nextInt();
        int a[] = new int[3005];
        for (int cas = 1; cas <= t; cas++) {
            int n = in.nextInt();
            int  i, j;
            for (i = 1; i <= n; ++i) {
                a[i] = in.nextInt();
            }
            BigInteger ans = BigInteger.valueOf(a[n]);
            BigInteger x = BigInteger.valueOf(1);
            BigInteger flag = BigInteger.valueOf(-1);
            n = n -1;
            for(i=1,j=n; i<=n; i++,j--)
            {
                x = x.multiply(BigInteger.valueOf(j)).divide(BigInteger.valueOf(i));
                x = x.multiply(flag);
                ans = ans.add(x.multiply(BigInteger.valueOf(a[j])));
            }
            System.out.println(ans);
        }
    }
}