program fractii;

var
  n, i, f, j, a, b, temp,s: longint;
  in_f, out_f: text;
  v:array[1..100000] of integer;

begin
  assign(in_f, 'fractii.in');
  assign(out_f, 'fractii.out');
  reset(in_f);
 
  readln(in_f, n);
 
     for i:=2 to n
    do
        v[i]:=i-1;
    
    for i:=2 to n
    do
      begin
         j := i+i;;
        
        while j<=n do
        begin  
          
         v[j]:=v[j]-v[i];
         j:=j+i;
    end;
    end;
    for i:=1 to n
    do
        s:=s+v[i];
    
   rewrite(out_f);
  write(out_f, s*2+1);
  close(out_f);
  
end.