var d,c:array[1..1000000]of longint;
    f:text;
    nr,r,i,j,n:longint;

begin
assign(f,'fractii.in');reset(f);
read(f,n);
close(f);
nr:=0;
assign(f,'fractii.out');rewrite(f);
for i:=1 to n do
  d[i]:=i;
for i:=2 to n do
  begin
    if c[i]=0 then
       begin
        j:=2;
        while j*i<=n do
          begin
          d[j*i]:=d[j*i]*(i-1) div i;
          c[j*i]:=1;
          j:=j+1;
          inc(nr);
          end;
    dec(d[i]);
    end;
    end;
    r:=0;
    for i:=2 to n do r:=r+d[i];
    write(f,r*2+1);
  close(f);
  writeln(nr);
  end.

close(f);