1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<string>
 5 
 6 using namespace std;
 7 const int maxn = 1000005;
 8 int rs[4][4], nex[maxn], a[maxn], b[maxn/100 + 5], n, m;
 9 void cal_next(int *str, int len)
10 {
11     nex[0] = -1; int k = -1;
12     for (int i = 1; i <= len - 1; i++) {
13         while (k > -1 && str[k + 1] != str[i])
14             k = nex[k];
15         if (str[k + 1] == str[i])k = k + 1;
16         nex[i] = k;
17     }
18 }
19 int KMP(int *a, int la, int  *b, int lb)
20 {
21     cal_next(b , lb);
22     int k = -1;
23     for (int i = 0; i < la; i++) {
24         while (k > -1 && b[k + 1] != a[i])
25             k = nex[k];
26         if (b[k + 1] == a[i])k = k + 1;
27         if (k == lb - 1)return i - lb + 1;
28     }
29     return -1;
30 }
31 int main()
32 {
33     ios::sync_with_stdio(false);
34     int T;
35     cin >> T;
36     while (T--) {
37         cin >> n >> m;
38         for (int i = 0; i < n; i++)cin >> a[i];
39         for (int i = 0; i < m; i++)cin >> b[i];
40         int ans = KMP(a, n, b, m);
41         if (ans != -1)cout << ans + 1 << endl;
42         else cout << "-1" << endl;
43     }
44     return 0;
45 }