x,l,i;main(n,y,u,j){scanf("%d",&n);for(y=u=n-1;n--;x=i++%2?++l:--u)for(j=n-~n;j--;i%2?x<=l?y+=y<u:x--:x>=u?y-=y>l:x++)printf("%d%d ",x,y);}