program Chei_si_Lacate;
var n:Longint;
procedure citeste;
var f:Text;
begin
Assign(f,'SEIF.IN'); Reset(f);
Readln(f,n); Close(f)
end;
procedure scrie;
var f:Text; i,j:Longint;
begin
Assign(f,'SEIF.OUT'); Rewrite(f);
Writeln(f,n*(n-1) div 2,' ',(n-1));
if (n=2) then begin
  writeln(f,1);
  writeln(f,1);
  end
else
for i:=1 to n-1 do
 for j:=i+1 to n do begin
   Writeln(f,i);
   writeln(f,j);
 end;
Close(f)
end;
Begin
citeste;
scrie
End.