#include <iostream>
using namespace std;
const int MAX_SIZE = 9;
int main() {
int n, m, mt[MAX_SIZE + 1][MAX_SIZE + 1];
cin >> n >> m;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
cin >> mt[i][j];
}
}
int middleElement = mt[n / 2 + 1][m / 2 + 1];
int flag = 1;
for (int i = 1; i <= n; ++i) {
if (mt[i][m / 2 + 1] != middleElement) {
flag = 0;
i = n + 1;
}
}
for (int j = 1; j <= m; ++j) {
if (mt[n / 2 + 1][j] != middleElement) {
flag = 0;
j = m + 1;
}
}
if (flag == 1) {
cout << "Da";
} else {
cout << "Nu";
}
return 0;
}
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