var f:text;
i,n,k:integer;
function prim(i:integer):boolean;
var j:integer;
begin
prim:=true;
for j:= 2 to trunc(sqrt(i)) do
if i mod j=0 then prim:=false;
end;
begin
assign(f,'fractii.in');
reset(f);
read(f,n);
close(f);
assign(f,'fractii.out');
rewrite(f);
k:=n*(n-1)+1;
for i := 2 to n do
if prim(i) then
k:=k-(n div i)*((n div i)-1);
write(f,k);
close(f);
end.