Reena had been given an array arr of positive integers of size N.Help her to find the value A.
A = arr[n]*arr[n] - arr[n-1]*arr[n-1] + arr[n-2]*arr[n-2] - ......... upto index 1
1. The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
2. The first line of each test case contains a single integer N.
3. The second line containsN space-separated positive integers represents array arr.
Output: For each test case, print the value of A in a single line
1. 1 <= T <= 10 2. 1 <= N <= 100000
3. 1 <= arr[i] <= 100