#include<iostream>
#include<string.h>
using namespace std;
int main()
{int i,j=0,ok=0;
char a[30],b[30];
cin>>a>>b;
for(i=0;i<strlen(b);i++)
{if(b[i]==a[j])
{ok++;
j++;}}
if(ok==strlen(a))
cout<<"DA";
else
cout<<"NU";}