program fracti;
var i,j:longint;
 f,g:text;
 sum,cod:real;
 n:integer;
 phi:array[1..10000]of real;
    begin
   assign(f,'fractii.in');reset(f);
   assign(g,'fractii.out');rewrite(g);
   readln(f,n);
   for i:=1 to n do phi[i]:=i;
   for i:=2 to n do
                  if(phi[i]=i) then
                                 for j:=i to n do begin
                                                    phi[j]:=phi[j]/i;
                                                    phi[j]:=phi[j]*(i-1);
                                                   end;
                     for i:=2 to n do  sum:= sum+phi[i];
    cod:=(2*sum)+1;
    write(g,cod);
    close(f);
    close(g);
   end.