Given two sequences of numbers : a, a, ...... , a[N], and b, b, ...... , b[M] (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number K which make a[K] = b, a[K + 1] = b, ...... , a[K + M - 1] = b[M]. If there are more than one K exist, output the smallest one.
The first line of input is a number T which indicate the number of cases. Each case contains three lines. The first line is two numbers N and M (1 <= M <= 10000, 1 <= N <= 1000000). The second line contains N integers which indicate a, a, ...... , a[N]. The third line contains M integers which indicate b, b, ...... , b[M]. All integers are in the range of [-1000000, 1000000].
For each test case, you should output one line which only contain K described above. If no such K exists, output -1 instead.