Alice is planning her travel route in a beautiful valley. In this valley, there are N lakes, and M rivers linking these lakes. Alice wants to start her trip from one lake, and enjoys the landscape by boat. That means she need to set up a path which go through every river exactly once. In addition, Alice has a specific number (a_1, a_2, ... , a_n) for each lake. If the path she finds is P_0 → P_1 → ... → P_t, the lucky number of this trip would be a_{P_0} XOR a_{P_1} XOR ... XOR a_{P_t}. She want to make this number as large as possible. Can you help her?
The first line of input contains an integer t, the number of test cases. t test cases follow.
For each test case, in the first line there are two positive integers N (N ≤ 100000) and M (M ≤ 500000), as described above. The i-th line of the next N lines contains an integer a_i(∀ i, 0 ≤ a_i ≤ 10000) representing the number of the i-th lake.
The i-th line of the next M lines contains two integers u_i and v_i representing the i-th river between the u_i-th lake and v_i-th lake. It is possible that u_i=v_i.
2 3 2 3 4 5 1 2 2 3 4 3 1 2 3 4 1 2 2 3 2 4
2 Impossible