#include<bits/stdc++.h>
using namespace std;
int main()
{
int t;
cin >> t;
while(t--)
{
int m;
cin >> m >> m;
string a,b;
cin >> a >> b;
int cnt=-1;
for(int i=0; i<=m/2+1;i++){
if(a.find(b)!=-1)
{
cnt = i;
break;
}else{
a=a+a;
}
}
cout << cnt << endl;
}
}
