A

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)
///DEBUG

int main()
{
    _test
    {
        int n, m;
        cin>>n>>m;

        string a, b;
        cin>>a>>b;

        int ans = -1;

        for(int i=0; i<=10; i++)
        {
            if(a.find(b) != string::npos)
            {
                ans = i;
                break;
            }

            a += a;
        }

        cout<<ans<<"\n";
    }
}