var n,i,j,k,l,c:longint;

begin
assign(input,'tije.in');reset(input);
assign(output,'tije.out');rewrite(output);
readln(n);
for i:=n-1 downto 1 do
        begin
        for j:=n downto 1 do
                for k:=1 to i do
                        writeln(j,' ',j+1);
        for k:=1 to i do
                writeln(n+1,' ',1);
        end;
close(input);close(output);
end.