program fractii;
var a:array[1..1000000] of longint;
    n,i,j,t,nr:longint;
    f:text;
    sum:int64;
begin
  assign(f,'fractii.in');
  reset(f);
  readln(f,n);
  close(f);
  for i:=1 to n do
    a[i]:=i-1;
  for i:=2 to n do
      begin
        t:=i+i;
        while t<=n do
          begin
            a[t]:=a[t]-a[i];
            t:=t+i;
          end;
      end;
  sum:=0;
  for i:=1 to n do
    sum:=sum+a[i];
  assign(f,'fractii.out');
  rewrite(f);
  writeln(f,sum*2+1);
  close(f);
end.