1540: Chocolate

In 2100, ACM chocolate will be one of the favorite foods in the world.
The ACM chocolate has too much type, each type of ACM chocolate is identified by a positive integer. One day, Sandy played a game on a big package of ACM chocolates which contains five colors (green, orange, brown, red and yellow). Each time he took one chocolate from the package and placed it on the table. If there were two chocolates of the same color on the table, he ate both of them.
At the begin of the game, there are n chocolates in the package. And at the end of the game, Sandy found there are only one chocolate on the table.
Now, tell you the n and n clocolates' type, do you know the identifier of the remain chocolate.

The input file for this problem contains several test cases. The first line of the input is a positive integer t(1<=t<=10) which is the number of cases that follow.
For each case, begins with a number n(1<=n<=100000). The next line is n numbers. Each number indicate a identifier of ACM chocolate. Two adjacent numbers separated by space.

For each test case, output a line with the answer.