#include <bits/stdc++.h>
#define nmax 50
using namespace std;
int a[nmax][nmax],n;
int main()
{
int i,j,verif=0;
cin>>n;
for(i=1;i<=n;i++)
for(j=1;j<=n;j++)
cin>>a[i][j];
///parcurgem
for(i=2;i<=n;i++)
for(j=i;j<=n;j++)
if(a[j][j-i+1]!=0)verif=1;
if(verif==1)
cout<<"nu"<<"\n";
else cout<<"da"<<"\n";
}