edfsh

#include <iostream>
#include <vector>
using namespace std;
int main() {
	int t, cnt=0;
	cin >> t;
	vector <vector < vector <int>>> a;
	for (int i = 0; i < t; i++) {
		int n, m;
		cin >> n >> m;
		for (int j = 0; j < n; j++) {
			for (int k = 0; k < m; k++) {
				cin >> a[i][j][k];
			}
		}
	}
	for (int i = 0; i < t; i++) {
		for (int j = 0; j < a[i].size()-1; j++) {
			for (int k = 0; k < a[i][j].size()-1; k++) {
				if (a[i][j][k] == a[i][j + 1][k] == a[i][j + 1][k + 1] == a[i][j][k + 1]) {
					cnt++;
				}
			}
		} if (cnt > 0) {
			cout << "NO" << endl;
		}
		else cout << "YES";
	}
	return 0;
}