type sir=array[1..1000000] of longint;
var n,s,i,j:longint;
a:sir;
f,g:text;
begin
assign(f,'fractii.in');reset(f);
assign(g,'fractii.out');rewrite(g);
readln(f,n);
for i:=2 to n do a[i]:=i-1;
  for i:=1 to n div 2 do
    begin
      j:=2*i;
      while j<=n do
        begin
          a[j]:=a[j]-a[i];
          j:=j+i;
        end;
    end;
  for i:=2 to n do s:=s+a[i];
  s:=s*2+1;
writeln(g,s);
close(g);
end.