Program cel;
var f,g:text;
    n,i,j:longint;
Begin
Assign(f,'lacate.in');Reset(f);
Assign(g,'lacate.out');Rewrite(g);
Read(f,n);
Writeln(g,((n-1)*n) div 2,' ',(n-1)*n);
For i:=1 to n-1 do
 For j:=i+1 to n do
  Writeln(g,i,' ',j);
Close(f);
Close(g);
end.