var a:array[1..100] of longint;
    i,j,k,n,s:longint;
    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:=2 to n do
  begin
  s:=s+a[i];
    j:=2*i;
    while j<=n do
      begin
        a[j]:=a[j]-a[i];
        j:=j+i;
      end;
  end;
s:=2*s+1;
writeln(g,s);
close(f);close(g);
end.