#include <iostream>
#include <string>
using namespace std;
 
// 判断是否可以通过删除一个区间得到 t
bool canBeMadeEqual(string& s, string& t) {
    int m = s.length(), n = t.length();
 
    // 尝试从前和后依次匹配
    int i = 0, j = 0;
 
    // 从左到右匹配 t
    while (i < m && j < n) {
        if (s[i] == t[j]) {
            j++;
        }
        i++;
    }
 
    // 如果 j == n，说明 t 完全匹配到了 s 的一部分
    if (j == n) {
        return true;
    }
 
    return false;
}
 
int main() {
    int T;
    cin >> T;
 
    while (T--) {
        int m, n;
        cin >> m >> n;
        string s, t;
        cin >> s >> t;
 
        if (canBeMadeEqual(s, t)) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
 
    return 0;
}
 

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