#include <iostream>
#include <string>
using namespace std;
 
bool isSubsequence(string s, string t) {
    int n = s.size(), m = t.size();
    int i = 0, j = 0;
 
    // 双指针法，遍历字符串 s 和 t
    while (i < n && j < m) {
        // 如果字符匹配
        if (s[i] == t[j]) {
            j++; // 移动 t 的指针
        }
        i++; // 始终移动 s 的指针
    }
 
    // 如果 j 遍历完 t，表示 t 是 s 的子序列
    return j == m;
}
 
int main() {
    int T; // 测试用例数
    cin >> T;
 
    while (T--) {
        int n, m;
        string s, t;
 
        cin >> n >> m;  // 输入字符串的长度
        cin >> s >> t;  // 输入字符串 s 和 t
 
        // 判断 t 是否为 s 的子序列
        if (isSubsequence(s, t)) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
 
    return 0;
}
 

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