program fractii_ia;
type vector=array [1..1000000] of int64;
var v:vector;
		f:text;
    i,m,n:longint;
    s:int64;

begin
assign(f,'fractii.in'); reset(f);
readln(f,n);
close(f);
for i:=1 to n do
	v[i]:=i-1;
for i:=2 to n do
	begin
  m:=2*i;
  while m<=n do
  	begin
    v[m]:=v[m]-v[i];
    m:=m+i
    end
  end;
s:=0;
for i:=1 to n do
	s:=s+v[i];
s:=2*s;
s:=s+1;
assign(f,'fractii.out'); rewrite(f);
writeln(f,s);
close(f)
end.