pb1_20102018

#include <iostream>

using namespace std;

int main()
{
    int n , V[105] , i , OK , OK1;
    cin >> n;
    OK1 = 0;
    for(i=1;i<=n;i++)
    {
        cin >> V[i];
        OK = 0;
        if(i>=2)
        {
            if(V[i]>=0&&V[i-1]<=0)
                OK = 1;
            if(V[i]<=0&&V[i-1]>=0)
                OK = 1;
        }
        if(OK==0&&i>=2){
            OK1 = 1;
        }
    }
    if(OK1==1)
        cout << "Nu";
    else
        cout << "Da";
    return 0;
}