#include <iostream>
#include <cstring>

using namespace std;
bool descentrate(char imp[],char par[]);
int main()
{
    char a[256];
    char *c,*b[256];

    int n=0;
    cin.getline(a,256);
     c=strtok(a," ");
      while(c)
    {
       b[++n]=c;
       c=strtok(0," ");
   }
   for(int i=1;i<n;++i)
        for(int j=i+1;j<=n;++j)
   {
        if(strlen(b[i])-strlen(b[j])==1&&strlen(b[i])%2==0)
            if(descentrate(b[j],b[i]))
            {
                cout<<"DA";
                return 0;
            }

        if(strlen(b[j])-strlen(b[i])==1&&strlen(b[j])%2==0)
            if(descentrate(b[i],b[j]))
            {
                cout<<"DA";
                return 0;
            }
   }
    cout<<"NU";
    return 0;
}
bool descentrate(char imp[],char par[])
{
    int n=strlen(imp)-1;
    for(int i=0;i<=n/2;++i)
        if(imp[i]!=par[i])
        return false;
    if(par[n/2]!=par[n/2+1])
        return false;
    for(int i=n/2+1;i<n;++i)
        if(imp[i]!=par[i+1])
        return false;
    return true;
}