program copii;
var n,i,j,g:integer;
    v:array[1..20,1..20]of integer;
    f,h:text;
begin
  assign(f,'copii.in');
  assign(h,'copii.out');
  reset(f);
  rewrite(h);
  read(f,n);
  for i:=1 to n do
      for j:=1 to n do
          read(f,v[i,j]);
  g:=1;
  g:=(n-1)*n div 2;
  if g=0 then g:=1;
  writeln(h,g);
  close(f);
  close(h);
end.