#include <iostream>
using namespace std;
int a,b,i,k,l,j,p,s;
int main()
{
cin >> a >> b;
for(i=b;i<=a;i++)
{
k=0;
l=0;
s++;
for(j=s;j<=i;j++)
{
k+=j;
l++;
if(k==a)
{
cout << "DA";
p++;
break;
}
if(l==b)
break;
}
if(k==a)
break;
}
if(p==0)
cout << "NU";
return 0;
}