sb prog 17

#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("matrice.in");
int n, a[51][51];

void read() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cin >> a[i][j];
        }
    }
}

int main() {
    read();
    int ok = 1;
    for (int i = 0; i < n - 1; i++) {
        for (int j = i + 1; j < n; j++) {
            if (a[i][j] != a[j][i]) {
                ok = 0;
            }
        }
    }
    cout << (ok ? "DA" : "NU") << endl;
    return 0;
}