#include <iostream>
#include <string>
using namespace std;
 
int main() {
    int T;  // Number of test cases
    cin >> T;
 
    while (T--) {
        int n, m;
        string s, t;
 
        cin >> n >> m;  // Lengths of strings s and t
        cin >> s >> t;  // Strings s and t
 
        int i = 0, j = 0;
        while (i < n && j < m) {
            if (s[i] == t[j]) {
                j++;  // Move to the next character in t
            }
            i++;  // Always move to the next character in s
        }
 
        // If we've matched all characters of t
        if (j == m) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
 
    return 0;
}
 

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4 2
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ad