Program man;
var fi, fo : text;
    i,n,q:longint;
    k:qword;
    a:array[0..1000000] of longint;
begin
     assign(fi,'fractii.in'); reset(fi); readln(fi,n); close(fi);
     assign(fo,'fractii.out'); rewrite(fo); for i:=0 to n-1 do a[i+1]:=i;
     k:=0;
    for i:=2 to (n div 2)+1 do  begin
                                q:=2*i; while q<=n do begin
                                                      a[q]:=a[q]-a[i];
                                                      q:=q+i;
                                                      end;
                                end;
    for i:=1 to n do k:=k+a[i];  k:=k*2+1;
     write(fo,k); close(fo);
end.