var
 f:text;
 rez,n,i,j,k,s,nr:longint;
begin
assign(f,'fractii.in');
reset(f);
read(f,n);
nr:=0;
for i:=2 to n do
   begin
    s:=i;
    while s+i<=n do  begin s:=s+i;writeln(i,'-',s,' ');
                         nr:=nr+1;
                   end;
   end;
rez:=n*n-(n-1)-2*nr;
assign(f,'fractii.out');rewrite(f);
writeln(f,rez);
close(f);
end.