#include <iostream>

using namespace std;

int v[500], n, x;

bool divide (int st, int dr) {
    if (st == dr) {
        if (v[st] != x) return false;
        else return true;
    } else {
        return divide(st, (st+dr)/2) && divide((st+dr)/2 + 1, dr);
    }
}

int main()
{
    cin >> n;

    for (int i = 0; i < n; i++) {
        cin >> v[i];
    }

    x = v[0];

    if(divide (0, n-1)) cout << "DA";
    else cout << "NU";

    return 0;
}