#include <iostream>
#include <string>
using namespace std;
 
bool isSubsequence(const string& s1, const string& s2, int l, int r) {
    int i = 0, j = 0;
    while (i < s1.length() && j < s2.length()) {
        if (i >= l && i < r && s1[i] == s2[j]) {
            j++;
        }
        i++;
    }
    return j == s2.length();
}
 
int main() {
    int T;
    cin >> T;
    while (T--) {
        int m, n;
        cin >> m >> n;
        string s1, s2;
        cin >> s1 >> s2;
 
        bool found = false;
        for (int i = 0; i <= m - n; i++) {
            if (isSubsequence(s1, s2, i, i + n)) {
                found = true;
                break;
            }
        }
        cout << (found ? "YES" : "NO") << endl;
    }
    return 0;
}
 

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