#include <iostream>
using namespace std;

int main() {
	int a, b, c, d;
    cin >> a >> b >> c >> d;
    if ( a * b == c && b * c ==d && d/c == c/b && c/b == b/a) {
        cout << "DA";
    } else {
        cout << "NU";
    }
    return 0;
}