var n,i,j,k:longint;
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 j:=1 to i do
writeln(f,'1',' ',n+1);
for k:=1 to n do
    for j:=1 to i do
writeln(f,k+1,' ',k);
end;}
writeln(f,n,' ',n+1);
for i:=n-1 downto 1 do begin
for j:=n downto 1 do
writeln(f,'1',' ',n+1);
for k:=1 to n do
writeln(f,n+1,' ',n-1);
end;
close(f);
end.