var n,i,j,c:integer;
    f,g:text;
begin
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
read(f,n);
c:=1;
for i:=2 to n do
 for j:=i-1 to n do if (j/i<>1) then inc(c);
write(g,c);
close(f);close(g);
end.