program fractii_4;
 var i,n,j:longint;
     s:int64;
     a:array [1..1000000] of longint;
     fi,fo:text;
begin
assign(fi,'fractii.in');
 reset(fi);
assign(fo,'fractii.out');
 rewrite(fo);
read(fi,n);
 for i:=1 to n do
  a[i]:=i-1;
 for i:=2 to (n div 2)+1 do  begin
                                j:=2*i;
                                while j<=n do begin
                                              a[j]:=a[j]-a[i];
                                              j:=j+i;
                                              end;
                                end;
 for i:=1 to n do
  s:=s+a[i];
 write(fo,2*s+1);
 close(fo);
end.