program pascal;
var f,g:text; v:array[1..1000000] of longint;
    i,n,j:longint;
    max:int64;

begin
assign(f,'fractii.in'); reset(f);
assign(g,'fractii.out'); rewrite(g);
read(f,n);
for i:=1 to n do v[i]:=i-1;
for i:=2 to n do
 begin
  j:=2*i;
  while j<=n do
       begin
       v[j]:=v[j]-v[i];
       j:=j+i;
       end;
  end;
 max:=0;
 for i:=2 to n do max:=max+v[i];
 max:=2*max+1;
 write(g,max);
 close(f);
 close(g);
end.