#include<iostream.h>
void main()
 {long n;
  int c,d,p=1;
  d=0;
  cin>>n;
  while(n)
   {c=n%10;
    if(c<d) p=0;
     n=n/10;
     d=c;
   }
 if(p==1) cout<<"da";
   else cout<<"nu";
 }