program p1;
var k,i,j,n,s:longint;
    a:array[1..1000001] of longint;
    fi,fo:text;

begin
assign(fi,'fractii.in'); reset(fi);
assign(fo,'fractii.out'); rewrite(fo);

  read(fi,n);

  for i:=2 to n do
   a[i]:=i-1;

  for i:=2 to n do
   if a[i]=i-1 then
                begin
                 j:=i; k:=1;
                 while j<=n do
                  begin
                   j:=j+i;
                   dec(a[j],k);
                   inc(k);
                  end;
                end;

  for i:=2 to n do
   inc(s,a[i]);

  write(fo,s*2+1);

close(fi); close(fo);
end.