curious students

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

ll mod = 1e9 + 7;

int main()
{
    ll t;
    cin >> t;
    while (t--)
    {
        ll n, k;
        cin >> n >> k;
        string a, b;
        cin >> a >> b;

        bool good = true;
        for (int i = 0; i + k - 1 < n; i++)
        {
            vector<ll> final1(26,0), final2(26,0);
            for (int j = i; j < i + k; j++)
            {
                final1[((int)a[j]) - 97]++;
                final2[((int)b[j]) - 97]++;
            }
            for (int j = 0; j < 26; j++)
            {
                if (final1[j] != final2[j])
                {
                    good = false;
                }
            }
        }

        if (good)
        {
            cout << "YES\n";
            continue;
        }
        cout << "NO\n";
    }
    return 0;
}