program eratostene;
 var f:array[1..1000000]of longint;
     n,i,j,s:longint;
     g:text;
 begin
  assign(g,'fractii.in');
  reset(g);
  readln(g,n);
  close(g);
  for i:=2 to n do
        f[i]:=i-1;
  for i:=1 to n div 2 do
  begin
     j:=2*i;
      while j<=n do
      begin
       f[j]:=f[j]-f[i];
       j:=j+i;
      end;
  end;
    for i:=2 to n do
        s:=s+f[i];
  assign(g,'fractii.out');
  rewrite(g);
  writeln(g,2*s+1);
  close(g);
 end.