text: #include <iostream>
  
  using namespace std;
  
  int n, a[200005], s=0;
  
  int main()
  {
  
      cin>>n;
  
      for(int i=1; i<=n; i++){
          cin>>a[i];
          s+=a[i];
      }
  
      if(s==(n*(n+1))/2) cout<<"DA";
      else cout<<"NU";
  
      return 0;
  }
  