#include <cstdio>

 #include <cctype>

 #define maxn 1000010

 #define maxm 10010

 int n, m;

 int aa[maxn], bb[maxm], f[maxm];

 void gn( int &rt ) {

     char ch;

     char opt;

     while( !isdigit(ch=getchar()) ) opt=ch;

     rt=ch-'';

     while( isdigit(ch=getchar()) )

         rt=rt*+ch-'';

     if( opt=='-' ) rt=-rt;

 }

 void getfail() {

     f[] = f[] = ;

     for( int i=, j; i<m; i++ ) {

         j = f[i];

         while( j && bb[i]!=bb[j] ) j=f[j];

         f[i+] = bb[i]==bb[j] ? j+ : ;

     }

 }

 int kmp() {

     for( int i=,j=; i<n; i++ ) {

         while( j && aa[i]!=bb[j] ) j=f[j];

         if( aa[i]==bb[j] ) j++;

         if( j==m ) return i-m+;

     }

     return -;

 }

 int main() {

     int T;

     scanf( "%d", &T );

     while( T-- ) {

         scanf( "%d%d", &n, &m );

         for( int i=; i<n; i++ )

             gn(aa[i]);

         for( int i=; i<m; i++ )

             gn(bb[i]);

         getfail();

         printf( "%d\n", kmp() );

     }

 }