1 #include<cstdio>
 2 #define MAXN 1000010
 3 int T[MAXN], P[MAXN/10], fail[MAXN/10], N, M, t;
 4 void getFail(){
 5     fail[0] = -1;
 6     for(int i = 1, j = -1;i < M;i ++){
 7         while(P[i] != P[j+1] && j >= 0) j = fail[j];
 8         if(P[i] == P[j+1]) j++;
 9         fail[i] = j;
10     }
11 }
12 void Kmp(){
13     getFail();
14     for(int i = 0, j = 0;i < N;i ++){
15         while(T[i] != P[j] && j) j = fail[j-1] + 1;
16         if(T[i] == P[j]) j++;
17         if(j == M){
18             printf("%d\n", i-M+2);
19             return;
20         }
21     }
22     printf("-1\n");
23 }
24 int main(){
25     scanf("%d", &t);
26     while(t--){
27         scanf("%d%d", &N, &M);
28         for(int i = 0;i < N;i ++) scanf("%d", T+i);
29         for(int i = 0;i < M;i ++) scanf("%d", P+i);
30         Kmp();
31     }
32     return 0;
33 }