为什么样例WA，交上去就全部AC？

#include <iostream>
using namespace std;
bool bool_int(char nm[][100], int j, int k) {
	for (int i = j; i < j + 4; i++) {
		for (int l = k; l < k + 4; l++) {
			if (i == j || i == j + 3 || l == k || l == k + 3) {
				if (nm[i][l] != '0') {
					return false;
				}
			} else {
				if (nm[i][l] != '1') {
					return false;
				}
			}
		}
	}
	return true;
}
int main() {
	int t;
	cin >> t;
	for (int i = 0; i < t; i++) {
		int n, m;
		cin >> n >> m;
		if (n < 4 || m < 4) {
			cout << "No\n";
			continue;
		}
		char nm[n][100];
		for (int j = 0; j < n; j++) {
			for (int k = 0; k < m; k++) {
				cin >> nm[j][k];
			}
		}
		bool Y_N = false;
		for (int j = 0; j <= n - 4; j++) {
			for (int k = 0; k <= m - 4; k++) {
				if (bool_int(nm, j, k)) {
					Y_N = true;
					break;
				}
			}
			if (Y_N) {
				break;
			}
		}
		if (Y_N) {
			cout << "Yes\n";
		} else {
			cout << "No\n";
		}
	}
	return 0;
}