var n,i,j,k:integer;   
    f:text;   
begin  
   assign(f,'tije.in');   
   reset(f);   
   read(f,n);   
   close(f);   
   assign(f,'tije.out');   
   rewrite(f);   
   for i:=n-1 downto 1 do  
   begin  
   for k:=1 to i do  
   writeln(f,1,' ',n+1);   
   for j:=1 to n do  
   for k:=1 to i do  
   writeln(f,j+1,' ',j);   
   end;   
   close(f);   
end.