var fi,fo:text;
    v:array[1..101]of byte;
    n,i,j:integer;
procedure rot;
var i,aux:integer;
begin
  aux:=v[n+1];
  for i:=n+1 downto 2 do
    begin
      v[i]:=v[i-1];
      writeln(fo,v[i],' ',i);
    end;
  writeln(fo,aux,' ',1);
  v[1]:=aux;
end;
procedure swap(poz,ct:integer);
var i:integer;
begin
  for i:=1 to n-ct+1 do
    writeln(fo,poz,' ',n+1);
  for i:=1 to n-ct+1 do
    writeln(fo,n+1,' ',poz);
end;
begin
  assign(fi,'tije.in'); reset(fi);
  assign(fo,'tije.out'); rewrite(fo);
  readln(fi,n);
  for i:=1 to n+1 do
    v[i]:=i;
  for i:=2 to n do
    begin
      rot;
      for j:=1 to n do
        swap(j,i);
    end;
  close(fi);
  close(fo);
end.