var f,g:text;
    i,j,n:longint;
    d,v:array[0..1000001] of longint;
begin
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
read(f,n);
//construiesc v[i]=v[i]-v[j],j=1..i-1 | i mod j=0
v[1]:=1;
v[2]:=1;
for i:=3 to n do begin
 v[i]:=i;
 for j:=1 to i-1 do
  if i mod j=0 then dec(v[i],v[j]);
end;
//fac dinamica
//construiesc d[i]=d[i-1]+v[i]
d[1]:=1;
d[2]:=3;
for i:=3 to n do
 d[i]:=d[i-1]+2*v[i];
writeln(g,d[n]);
close(f);
close(g);
end.